E P A/600/R-00/099 
March 2001 


LlbKHKY Ul- CONURESS 

MLCM 


2006/02671 

:PA 


FT MEADE 
GenCol1 




.^arch and Development 


United States Office of Research and 

Environmental Protection Development 

Agency Washington DC 20460 

Sources, Emission and 
Exposure for 

Trichloroethylene (TCE) and 
Related Chemicals 













EPA/600/R-00/099 
March 2001 







\ 


OCT 29.200 1 


/ 






SOURCES, EMISSION AND EXPOSURE FOR 
TRICHLOROETHYLENE (TCE) 

AND RELATED CHEMICALS 


National Center for Environmental Assessment-Washington Office 
Office of Research and Development 
U.S. Environmental Protection Agency 
Washington, DC 20460 



/T"'y Recycled/Recyclable 

Printed with vegetable- 


paper that contains a minimum of 
50% post-consumer fiber content 
processed chlorine free. 


with vegetable-based ink on 



DISCLAIMER 


LIBRARY OF CONGRESS 

MLCH 

2006/02671 


This report has been reviewed in accordance with U.S. Environmental Protection Agency 
policy and approved for publication. Mention of trade names or commercial products does not 
constitute endorsement or recommendation for use. 


LC Control Number 



2001 344253 






TABLE OF CONTENTS 


LIST OF TABLES. x 

LIST OF FIGURES.xi 

PREFACE . xii 

AUTHORS, CONTRIBUTORS, AND REVIEWERS.xiii 

SECTION A. SUMMARY AND INTRODUCTION.1 

SUMMARY.1 

INTRODUCTION.10 

SECTION B. PARENT COMPOUNDS .13 

1.0 TRICHLOROETHYLENE .13 

1.1 CHEMICAL AND PHYSICAL PROPERTIES .13 

1.1.1 Nomenclature.13 

1.1.2 Formula and Molecular Weight.13 

1.1.3 Chemical and Physical Properties.13 

1.1.4 Technical Products and Impurities.14 

1.2 PRODUCTION AND USE.14 

1.2.1 Production .14 

1.2.2 Uses.14 

1.2.3 Disposal.15 

1.3 POTENTIAL FOR HUMAN EXPOSURE.15 

1.3.1 Natural Occurrence .15 

1.3.2 Occupational Exposure .15 

1.3.3 Environmental .15 

1.4 HUMAN EXPOSURE AND POPULATION ESTIMATES .23 

1.4.1 General U.S. Population . 23 

1.4.2 Occupational Exposure .26 

1.4.3 Consumer Exposure.27 

1.5 CHAPTER SUMMARY.27 

2.0 TETRACHLOROETHYLENE (PERCHLOROETHYLENE).30 

2.1 CHEMICAL AND PHYSICAL PROPERTIES .30 

2.1.1 Nomenclature.30 

2.1.2 Formula and Molecular Weight.30 

2.1.3 Chemical and Physical Properties. 30 

2.1.4 Technical Products and Impurities.31 

2.2 PRODUCTION AND USE.31 


m 




































TABLE OF CONTENTS (continued) 


2.2.1 Production .31 

2.2.2 Uses.32 

2.2.3 Disposal.32 

2.3 POTENTIAL FOR HUMAN EXPOSURE.32 

2.3.1 Natural Occurrence .32 

2.3.2 Occupational .32 

2.3.3 Environmental.33 

2.4 HUMAN EXPOSURE AND POPULATION ESTIMATES .40 

2.4.1 General U.S. Population .40 

2.4.2 Occupational Exposure .41 

2.4.3 Consumer Exposure.41 

2.5 CHAPTER SUMMARY.41 

3.0 1,1,1 -TRICHLOROETHANE (METHYL CHLOROFORM).44 

3.1 CHEMICAL AND PHYSICAL PROPERTIES .44 

3.1.1 Nomenclature.44 

3.1.2 Formula and Molecular Weight.44 

3.1.3 Chemical and Physical Properties.44 

3.1.4 Technical Products and Impurities.45 

3.2 PRODUCTION AND USE.45 

3.2.1 Production .45 

3.2.2 Uses.46 

3.2.3 Disposal.46 

3.3 POTENTIAL FOR HUMAN EXPOSURE.46 

3.3.1 Natural Occurrence .46 

3.3.2 Occupational .46 

3.3.3 Environmental .47 

3.4 HUMAN EXPOSURE AND POPULATION ESTIMATES .52 

3.4.1 General U.S. Population .52 

3.4.2 Occupational Exposure .52 

3.4.3 Consumer Exposure .54 

3.5 CHAPTER SUMMARY.54 

4.0 1,2-DICHLOROETHYLENE.56 

4.1 CHEMICAL AND PHYSICAL PROPERTIES .56 

4.1.1 Nomenclature.56 

4.1.2 Formula and Molecular Weight.56 

4.1.3 Chemical and Physical Properties.56 

4.1.4 Technical Products and Impurities.57 

4.2 PRODUCTION AND USE.57 

4.2.1 Production .57 

4.2.2 Uses.57 

4.2.3 Disposal.58 

4.3 POTENTIAL FOR HUMAN EXPOSURE.58 


IV 












































TABLE OF CONTENTS (continued) 


4.3.1 Natural Occurrence .58 

4.3.2 Occupational .58 

4.3.3 Environmental .58 

4.4 HUMAN EXPOSURE AND POPULATION ESTIMATES .62 

4.4.1 General U.S. Population . 62 

4.4.2 Occupational Exposure .62 

4.4.3 Consumer Exposure.64 

4.5 CHAPTER SUMMARY.64 

5.0 CIS-1,2-DICHLOROETHYLENE .65 

5.1 CHEMICAL AND PHYSICAL PROPERTIES .65 

5.1.1 Nomenclature.65 

5.1.2 Formula and Molecular Weight.65 

5.1.3 Chemical and Physical Properties.65 

5.1.4 Technical Products and Impurities.66 

5.2 PRODUCTION AND USE.66 

5.2.1 Production .66 

5.2.2 Uses.66 

5.2.3 Disposal.67 

5.3 POTENTIAL FOR HUMAN EXPOSURE.67 

5.3.1 Natural Occurrence .67 

5.3.2 Occupational . 67 

5.3.3 Environmental .67 

5.4 HUMAN EXPOSURE AND POPULATION ESTIMATES .70 

5.4.1 General U.S. Population .70 

5.4.2 Occupational Exposure .70 

5.4.3 Consumer Exposure.70 

6.0 TRANS-1,2-DICHLOROETHYLENE.71 

6.1 CHEMICAL AND PHYSICAL PROPERTIES .71 

6.1.1 Nomenclature.71 

6.1.2 Formula and Molecular Weight.71 

6.1.3 Chemical and Physical Properties.71 

6.1.4 Technical Products and Impurities.72 

6.2 PRODUCTION AND USE. : .72 

6.2.1 Production .72 

6.2.2 Uses.72 

6.2.3 Disposal.73 

6.3 POTENTIAL FOR HUMAN EXPOSURE.73 

6.3.1 Natural Occurrence .73 

6.3.2 Occupational .73 

6.3.3 Environmental . 73 

6.4 HUMAN EXPOSURE AND POPULATION ESTIMATES .76 

6.4.1 General U.S. Population .76 


v 












































TABLE OF CONTENTS (continued) 

6.4.2 Occupational Exposure .76 

6.4.3 Consumer Exposure.76 

7.0 1,1,1,2-TETRACHLOROETHANE .77 

7.1 CHEMICAL AND PHYSICAL PROPERTIES .77 

7.1.1 Nomenclature.77 

7.1.2 Formula and Molecular Weight.77 

7.1.3 Chemical and Physical Properties.77 

7.1.4 Technical Products and Impurities.78 

7.2 PRODUCTION AND USE.78 

7.2.1 Production . 78 

7.2.2 Uses.78 

7.2.3 Disposal.79 

7.3 POTENTIAL FOR HUMAN EXPOSURE.79 

7.3.1 Natural Occurrence .79 

7.3.2 Occupational .79 

7.3.3 Environmental .79 

7.4 HUMAN EXPOSURE AND POPULATION ESTIMATES .81 

7.4.1 General U.S. Population .81 

7.4.2 Occupational Exposure .82 

7.4.3 Consumer Exposure.82 

7.5 CHAPTER SUMMARY.82 

8.0 1,1 -DICHLOROETHANE.83 

8.1 CHEMICAL AND PHYSICAL PROPERTIES .83 

8.1.1 Nomenclature.83 

8.1.2 Formula and Molecular Weight.83 

8.1.3 Chemical and Physical Properties.83 

8.1.4 Technical Products and Impurities.84 

8.2 PRODUCTION AND USE.84 

8.2.1 Production .84 

8.2.2 Uses.84 

8.2.3 Disposal.84 

8.3 POTENTIAL FOR HUMAN EXPOSURE.85 

8.3.1 Natural Occurrence .85 

8.3.2 Occupational .85 

8.3.3 Environmental .85 

8.4 HUMAN EXPOSURE AND POPULATION ESTIMATES .88 

8.4.1 General U.S. Population .88 

8.4.2 Occupational Exposure .88 

8.4.3 Consumer Exposure.88 

8.5 CHAPTER SUMMARY.90 

SECTION C. METABOLITES OF TRICHLOROETHYLENE 

AND PARENT COMPOUNDS .91 

vi 











































TABLE OF CONTENTS (continued) 


9.0 CHLORAL.91 

9.1 CHEMICAL AND PHYSICAL PROPERTIES .91 

9.1.1 N omenclature.91 

9.1.2 Formula and Molecular Weight.91 

9.1.3 Chemical and Physical Properties.91 

9.1.4 Technical Products and Impurities.92 

9.2 PRODUCTION AND USE.92 

9.2.1 Production .92 

9.2.2 Uses.93 

9.2.3 Disposal.93 

9.3 POTENTIAL FOR HUMAN EXPOSURE.93 

9.3.1 Natural Occurrence .93 

9.3.2 Occupational .93 

9.3.3 Environmental .94 

9.4 HUMAN EXPOSURE AND POPULATION ESTIMATES .96 

9.4.1 General U.S. Population .96 

9.4.2 Occupational Exposure .96 

9.4.3 Consumer Exposure.96 

9.5 CHAPTER SUMMARY.96 

10.0 CHLORAL HYDRATE.98 

10.1 CHEMICAL AND PHYSICAL PROPERTIES .98 

10.1.1 Nomenclature.98 

10.1.2 Formula and Molecular Weight.98 

10.1.3 Chemical and Physical Properties.98 

10.1.4 Technical Products and Impurities.99 

10.2 PRODUCTION AND USE.99 

10.2.1 Production .99 

10.2.2 Uses.100 

10.2.3 Disposal.100 

10.3 POTENTIAL FOR HUMAN EXPOSURE.100 

10.3.1 Natural Occurrence .100 

10.3.2 Occupational .100 

10.3.3 Environmental .100 

10.4 HUMAN EXPOSURE AND POPULATION ESTIMATES .102 

10.5 CHAPTER SUMMARY.102 

11.0 MONOCHLOROACETIC ACID.103 

11.1 CHEMICAL AND PHYSICAL PROPERTIES .103 

11.1.1 Nomenclature.103 

11.1.2 Formula and Molecular Weight.103 

11.1.3 Chemical and Physical Properties. 103 

11.1.4 Technical Products and Impurities.104 

11.2 PRODUCTION AND USE.104 

vii 












































TABLE OF CONTENTS (continued) 

11.2.1 Production .104 

11.2.2 Uses .104 

11.2.3 Disposal.104 

11.3 POTENTIAL FOR HUMAN EXPOSURE.105 

11.3.1 Natural Occurrence .105 

11.3.2 Occupational .105 

11.3.3 Environmental .105 

11.4 HUMAN EXPOSURE AND POPULATION ESTIMATES .107 

11.5 CHAPTER SUMMARY.107 

12.0 DICHLOROACETIC ACID.109 

12.1 CHEMICAL AND PHYSICAL PROPERTIES .109 

12.1.1 Nomenclature.109 

12.1.2 Formula and Molecular Weight.109 

12.1.3 Chemical and Physical Properties.109 

12.1.4 Technical Products and Impurities.110 

12.2 PRODUCTION AND USE . ..110 

12.2.1 Production .110 

12.2.2 Uses.110 

12.2.3 Disposal.110 

12.3 POTENTIAL FOR HUMAN EXPOSURE.110 

12.3.1 Natural Occurrence .110 

12.3.2 Occupational .110 

12.3.3 Environmental.Ill 

12.4 HUMAN EXPOSURE AND POPULATION ESTIMATES .112 

12.4.1 General U.S. Population .112 

12.4.2 Occupational Exposure .112 

12.4.3 Consumer Exposure.112 

12.5 CHAPTER SUMMARY.112 

13.0 TRICHLOROACETIC ACID.113 

13.1 CHEMICAL AND PHYSICAL PROPERTIES .113 

13.1.1 Nomenclature.113 

13.1.2 Formula and Molecular Weight.113 

13.1.3 Chemical and Physical Properties.113 

13.1.4 Technical Products and Impurities.114 

13.2 PRODUCTION AND USE.114 

13.2.1 Production .114 

13.2.2 Uses .114 

13.2.3 Disposal.115 

13.3 POTENTIAL FOR HUMAN EXPOSURE.115 

13.3.1 Natural Occurrence .115 

13.3.2 Occupational .115 

13.3.3 Environmental .115 


Vlll 












































TABLE OF CONTENTS (continued) 


13.4 HUMAN EXPOSURE AND POPULATION ESTIMATES .118 

13.4.1 General U.S. Population .118 

13.4.2 Occupational Exposure .118 

13.4.3 Consumer Exposure.118 

13.5 CHAPTER SUMMARY.118 

14.0 DICHLORO-VINYL CYSTEINE.119 

REFERENCES .120 


IX 









LIST OF TABLES 


Table A-l. Summary of Potential Exposure Pathways and Potentially 

Exposed Populations .5 

Table A-2. Preliminary Dose Estimates of TCE and Related Chemicals .8 

Table A-3. Summary of U.S. Production Data.9 

Table 1-1. Annual Releases of Trichloroethylene in the U.S. (lbs).16 

Table 1-2. Concentrations of Trichloroethylene in Ambient Air .17 

Table 1-3 Mean TCE Air Levels Across Monitors by Year.18 

Table 1 -4 Mean TCE Air Levels Across Monitors by Land 

Setting and Use (1985 to 1998). 18 

Table 1-5 Modeled TCE Air Concentrations in Continental U.S. for 1990 . 18 

Table 1-6. Concentrations of Trichloroethylene in Water.21 

Table 1-7. TCE Levels in Whole Blood by Population Percentile.22 

Table 1-8. Modeled Exposure Estimates for TCE .25 

Table 1-9. Comparison of Measured and Modeled TCE Concentrations.25 

Table 1-10. Trichloroethylene Summary.29 

Table 2-1. Releases of Tetrachloroethylene (lbs).33 

Table 2-2. Concentrations of Tetrachloroethylene in Ambient Air.34 

Table 2-3. Concentrations of Tetrachloroethylene in Water.35 

Table 2-4. Tetrachloroethylene Levels in Whole Blood by Population 

Percentile.37 

Table 2-5. Modeled Exposure Estimates for Tetrachloroethylene .38 

Table 2-6. Comparison of Measured and Modeled Perchloroethylene 

Concentrations.38 

Table 2-7. Tetrachloroethylene (Perchloroethylene) Summary.43 

Table 3 -1. Releases of 1,1,1 -Trichloroethane (lbs).47 

Table 3-2. Level of 1,1,1-Trichloroethane in Food.49 

Table 3-3. 1,1,1-Trichloroethane in Common Household Products.54 

Table 3-4. 1,1,1-Trichloroethane (Methyl Chloroform) Summary.55 

Table 4-1. 1,2-Dichloroethylene Summary.64 

Table 7-1. 1,1,1,2-Tetrachloroethane Summary.82 

Table 8-1. 1,1-Dichloroethane Summary .90 

Table 9-1. Concentrations of Chloral (As Chloral Hydrate) 

in Drinking Water in the United States.94 

Table 9-2. Chloral Summary.97 

Table 10-1. Chloral Hydrate Summary.102 

Table 11-1. Release of Chloroacetic Acid (lbs/yr).105 

Table 11-2. Monochloroacetic Acid Summary.108 

Table 12-1. Concentrations of Dichloroacetic Acid in Water.Ill 

Table 12-2. Dichloroacetic Acid Summary.112 

Table 13-1. Concentrations of Trichloroacetic Acid in Water .116 

Table 13-2. Trichloroacetic Acid Summary .118 


x 






































LIST OF FIGURES 


Figure A-l. Trichloroethylene, Related Parent Compounds, 

and Their Metabolites .11 

Figure 1 -1. Modeled TCE Levels in Air from Cumulative 

Exposure Project by Census Tract, New Jersey .19 

Figure 1-2. Frequency of NPL Sites with Trichloroethylene Contamination.28 

Figure 2-1. Concentration of Tetrachloroethylene in Blood at 

Selected Population Percentiles.36 

Figure 2-2. Frequency of NPL Sites with Tetrachloroethylene Contamination.42 

Figure 3-1. Concentration of 1,1,1-Trichloromethane in Blood at 

Selected Population Percentiles. 50 

Figure 3-2. Frequency of NPL Sites with 1,1,1-Trichloromethane Contamination.53 

Figure 4-1. Frequency of NPL Sites with 1,2-Dichloroethene (Unspecified) 

Contamination.63 

Figure 8-1. Frequency of NPL Sites with 1,1-Dichloroethane Contamination .89 


xi 











PREFACE 


This document was based mostly on the report, “Sources, Emission and Exposure for 
Trichloroethylene (TCE)” which was prepared in August 1997 by the Versar, Inc. of Springfield, 
Virginia under U.S. Environmental Protection Agency (EPA) Contract No. 68-D5-0051. 
Additional information was later added/updated, especially for the Trichloroethylene chapter. 

This document is published as a state-of-the-science report on the exposure assessment of 
TCE, its metabolites and other related chemicals known to produce similar metabolites. A 
summary of much of the information contained in this report was also published in 
Environmental Health Perspectives, Supplements, May 2000 and underwent the peer review 
process required by the journal. 

The scientific literature search for this assessment is generally current through January 
1997, although a number of more recent publications on key topics have been included. 


xn 


AUTHORS, CONTRIBUTORS, AND REVIEWERS 


Authors 

This report was prepared by Versar, Inc. of Springfield, VA, for the National Center for 
Environmental Assessment-Washington Office (NCEA-W) of EPA’s Office of Research and 
Development. Dr. Chieh Wu (NCEA-W) served as the Work Assignment Manager for this 
contract as well as a contributing author. John Schaum (NCEA-W) was also a contributing 
author. 

Reviewers 

A summary of this report was published in Environmental Health Perspective, Volume 
108, Supplement 2 in May 2000 by Wu and Schaum. This journal sponsored a peer review of 
this article by their independent reviewers. Other reviewers of this document are listed below: 

EPA reviewers: 


Cheryl Scott 

National Center for Environmental Assessment 
Mike Dusetzina 

Office of Air Quality Planning and Standards 
External reviewers: 


Dr. C.P. Huang 

Chair and Distinguished Professor of Environmental Engineering 
University of Delaware 

Dr. Uwe Schneider 
Environmental Quality Branch 
Environment Canada 

Dr. Mildred Williams-Johnson 

Agency for Toxic Substances and Disease Registry 

U.S. Department of Health and Human Services 

Acknowledgments 

The authors wish to thank Cheryl Scott and Mike Dusetzina for their review and 
comments of the draft report, and Susan Perlin of NCEA-W and David Wong of George Mason 
University for their assistance in the use of the Geographic Information System (GIS) modeling 
to map the air concentrations in New Jersey. The authors also would like to thank all the 
reviewers for their time and efforts. 


xm 







































































































SECTION A. SUMMARY AND INTRODUCTION 


SUMMARY 

This report is an exposure assessment of Trichloroethylene (TCE), its metabolites, and 
other chemical compounds known to produce identical metabolites. In addition to TCE, other 
parent compounds considered here are 1,1,1-trichloroethane (methyl chloroform), 
tetrachloroethylene (PCE or PERC), 1,2-dichloroethylene (cis-, trans-, and mixed isomers), 
1,1,1,2-tetrachloroethane, and 1,1-dichloroethane. The metabolites are chloral, chloral hydrate, 
monochloroacetic acid, dichloroacetic acid, trichloroacetic acid, and dichloro-vinyl cysteine 
(DCVC). Although listed here, no information was found for the metabolite, DCVC. 

The parent compounds are used in many diverse manufacturing industries such as food 
processing, textiles, wood products, furniture and fixtures, paper, printing and publishing, 
chemicals, petroleum, rubber, leather, stone and clay, primary metals, fabricated metals, 
industrial machinery, electronics, and transportation equipment. They are primarily used as 
solvents, carriers, or extractants; in dry cleaning of textiles; in metal cleaning and degreasing; in 
textile manufacturing; as insulating fluids/coolants; and as chemical intermediates. The 
metabolites have more restricted uses in industry as chemical intermediates, herbicides, and 
pharmaceuticals. 

The major routes of exposure for these chemicals are inhalation, ingestion, and dermal 
absorption. The following paragraphs summarize available information concerning the general 
population, occupational, and consumer exposure to these chemicals. A summary of the 
potential exposure pathways and potential exposed populations for each chemical is presented in 
Table A-l. Although inhalation seems to be the dominant route of exposure for most of the 
chemicals, exposure can also occur through the ingestion of contaminated foods and drinking 
water and through dermal contact (spills). Using media levels of the chemicals considered here, 
one may predict the range of estimated exposures and the estimated range of daily doses. These 
values are presented in Table A-2. 

More research is needed to assess the exposure of these chemicals for the non- 
occupational population (IARC, 1995; ATSDR, 1990, 1995, 1996a,b, 1997a,b). Most of the 
monitoring data for humans are from occupational studies of specific workers exposed to the 
chemical. Current data are needed for all chemicals for production, use in consumer products, 
releases, and the efficiency of current disposal practices. Additionally, more data are needed on 
the degradation of these chemicals in groundwater (specifically TCE, PCE, 1,1,1-trichloroethane, 
and 1,2-dichloroethylene) and their rates of transformation in the soil. Current data to 
characterize the levels of these chemicals in air, water, soil, and food also are needed. Current 
monitoring data for these media will aid in the assessment of exposure for the general population, 
especially persons living near waste sites. Biological monitoring data are also needed for 
humans. Because TCE and PCE have been detected in breast milk samples (NHANES III, 1997) 
of the general population, children ages 12 months and less who ingest breast milk may 
potentially be exposed. Unspecified levels of TCE have been found in breast milk, however, 
levels of PCE detected have ranged up to 43 pg/1 in the general population. According to NAS 


1 


(1991), in 1989, the initiation of breast-fed newborn infants in the hospital was reported to 52.2 
percent and by age 5-6 months, only 19.6 percent of the infants were breast-fed. Since some of 
these chemicals (e.g., TCE and PCE) are present in soil, children may be exposed through 
activities such as playing in or ingesting soil. Table A-3 presents the production data 
(production, import, and export). As shown in this table, however, most of the production data 
are old or non-existent. 

T richloroethylene 

The general U.S. population is exposed via inhalation, ingestion, or dermal pathways. 

The most important pathways appear to be inhalation of contaminated ambient air and ingestion 
of contaminated drinking water. Because of pervasiveness of TCE in the environment, most 
people are exposed to low levels of TCE. Occupational exposure results primarily from its use 
as a degreasing or metal cleaning agent. Workers in the vapor degreasing industry are exposed to 
the highest levels through inhalation. Consumers are exposed through their use of wood stains, 
varnishes, finishes, lubricants, adhesives, typewriter correction fluid, paint removers, and 
cleaners that contain TCE. Levels of TCE in consumer products appear to be declining. 

Elevated exposure may occur to people living near waste facilities, those being exposed through 
occupational activities, and residents of some urban and industrial areas where TCE- 
contaminated media occur. Since TCE has been detected in breast milk, nursing infants may be 
exposed via this pathway. 

Tetrachloroethylene (Perchloroethylene; PCE) 

The general U.S. population is exposed to PCE via inhalation and ingestion. The most 
important pathways appear to be inhalation of contaminated ambient air (including indoor air) 
and ingestion of contaminated drinking water. Dermal exposure does not appear to be important. 
The greatest chance of exposure is occupational, primarily through inhalation, especially in the 
dry cleaning industry. Consumers may be exposed through the use of adhesives, water 
repellents, fabric finishes, spot removers, and wood cleaners. Since PCE has been detected in 
breast milk, nursing infants may be exposed via this pathway. 

1,1,1-Trichloroethane (methyl chloroform) 

The general U.S. population is exposed to this chemical via inhalation of ambient air 
(including indoor air). Exposure can also occur through ingestion of contaminated foods and 
drinking water and through dermal contact. Exposure from commercial products may be more 
significant than exposure resulting from industrial releases. Occupational exposure results from 
degreasing, electric component manufacture, mixing and application of commercial resins, spray 
painting and gluing. Occupational exposure is primarily through inhalation pathway. Consumers 
are exposed via use of a wide variety of household products such as fingernail polish, paint 
thinner, caulking compounds, paint removers, and antifreeze. 


2 


1.2- Dichloroethylene (cis-, trans-, and mixed isomers) 

The general U.S. population is exposed to this chemical via the inhalation of 
contaminated ambient air and from ingestion of water from contaminated groundwater sources. 
Potentially high exposures are possible to those living near production/processing facilities, 
municipal wastewater sites, hazardous waste sites, and municipal landfills. The National 
Institute for Occupational Safety and Health (NIOSH) estimates that a small number of workers 
(about 275) are potentially exposed occupationally via an inhalation or dermal pathway to one or 
both of the isomers. No data are available for consumer exposure. 

1.1.1.2- T etrachloroethane 

The general U.S. population is exposed to this compound thorough the inhalation of 
ambient air. No data are available for occupational exposures. Consumers are possibly exposed 
through their use of paints and varnishes, but confirmatory data are not available. 

1,1-Dichloroethane 

The general U.S. population is exposed to this chemical via the inhalation of ambient air 
and the ingestion of contaminated drinking water. Higher exposures may exist for persons living 
near industrial and hazardous waste sites. Occupational exposure occurs primarily via inhalation 
during manufacturing processes using 1,1,-dichloroethane as a chemical intermediate, solvent, 
and component of fumigant formulations. No data are available for consumer exposure. 

Chloral 

The general U.S. population may be exposed to chloral from drinking chlorinated water 
and from pharmaceutical use. Some occupational exposure may result from chloral's production 
and manufacture. No data are available for consumer exposure. 

Chloral hydrate 

The general U.S. population may be exposed to chloral hydrate from drinking chlorinated 
water and from pharmaceutical use. No data are available for consumer exposure. 

Monochloroacetic acid 

No data are available for general U.S. population, occupational, and consumer exposure. 

Dichloroacetic acid 

The general U.S. population is exposed to this compound to this chemical via ingestion of 
chlorinated drinking water and chlorinated water in swimming pools. No data are available for 
occupational and consumer exposure. 


Trichloroacetic acid 


The general U.S. population is exposed to this chemical via the ingestion of contaminated 
drinking water and foods. Occupational exposure may occur during the production and use of 
trichloroacetic acid as a pesticide. No data are available for consumer exposure. 

Dichloro-Vinyl Cysteine 

There are no data for this chemical. 


4 



5 





















Table A-l. Summary of Potential Exposure Pathways and Potentially Exposed Populations (continued) 


/i 



6 


NA = Information not available. 
























Table A-l. Summary of Potential Exposure Pathways and Potentially Exposed Populations (continued) 


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Table A-2. Preliminary Dose Estimates of TCE and Related Chemicals 


Chemical 

Population 

Media 

Range of Estimated Adult 
Exposures 
(ug/day) 

Range of Adult Doses 
(mg/kg/day) 

Data Sources 

Trichloroethylene 

General 

Air 

11-33 

1.57E-04 — 4.71E-04 

ATSDR (1997a) 

General 

Water 

2-20 

2.86E-05 — 2.86E-04 

ATSDR (1997a) 

Occupational 

Air 

2,232 - 9,489 

3.19E-02 - 1.36E-01 

ATSDR (1997a) 

Tetrachloroethylene (PERC) 

General 

Air 

80 - 200 

1.14E-03 — 2.86E-03 

ATSDR (1997b) 

General 

Water 

0.1 -0.2 

1.43E-06 — 2.86E-06 

ATSDR (1997b) 

Occupational 

Air 

5,897 -219,685 

8.43E-02 -3.14 

ATSDR (1997b) 

1,1,1 -T richloroethane 

General 

Air 

10.8 — 108 

1.54E-04 - 1.54E-03 

ATSDR (1995) 

General 

Water 

0.38-4.2 

5.5E-06 - 6.00E-05 

ATSDR (1995) 

1,2-Dichloroethylene 

General 

Air 

1 -6 

1.43E-05 — 8.57E-05 

ATSDR (1996a) 

General 

Water 

2.2 

3.14E -05 

ATSDR (1996a) 

Cis-1,2-Dichloroethylene 

General 

Air 

5.4 

7.71E-05 

HSDB (1996) 

General 

Water 

*/~i 

1 

o 

7.14E-06 — 7.71E-05 

HSDB (1996) 

1,1,1,2-Tetrachloroethane 

General 

Air 

142 

2.03E -03 

HSDB (1996) 

1,1-Dichloroethane 

General 

Air 

4 

5.71E-05 

ATSDR (1990) 

General 

Water 

2.47 - 469.38 

3.53E-05 — 6.71E-03 

ATSDR (1990) 

Chloral 

General 

Water 

0.02-36.4 

2.86E-07 - 5.20E-04 

HSDB (1996) 

Monochloroacetic Acid 

General 

Water 

2 - 2.4 

2.86E-05 — 3.43E-05 

USEPA (1994) 

Dichloroacetic Acid 

General 

Water 

10-266 

1.43E-04 — 3.80E-03 

IARC (1995) 

Trichloroacetic Acid 

General 

Water 

8.56-322 

1.22E-03 — 4.60E-03 

1ARC (1995) 


8 







































Table A-3. Summary of U.S. Production Data 


Chemical 

U.S. Production Data (kilograms) 

Production (yr) 

Import (yr) 

Export (yr) 

TCE 

1.17 x 10 5 (1981) 

7.72 x 10 7 (198 5) 

1.45 x 10 8 (1991) 

1.98 x 10 7 (198 5) 

1.06 x 10 7 (1985) 

PCE 

3.08 x 10* (1985) 

1.84 x 10* (1986) 

2.14 x 10 8 (1989) 

1.60 x 10 s (1990) 

1.08 x 10 8 (1991) 

1.12 x 10 8 (1992) 

1.23 x 10 8 (1993) 

1.70 x 10 7 (1982) 

6.36 x 10 7 (1985) 

8.3 x 10 4 (1986) 

2.47 x 10 7 (1983) 

9.84 x 10 6 (1985) 

1,1,1-Trichloroethane 

3.64 x 10 8 (1990) 

3.13 x 10 8 (1992) 

4.54 x 10 4 (1981) 

5.99 x 10 6 (1992) 

9.08 x 10 4 (1993) 

5.20 x 10 7 (1990) 

7.39 x 10 7 (1991) 

6.34 x 10 7 (1992) 

3.44 x 10 7 (1993) 

1,2-Dichloroethylene 

NA 

NA 

NA 

Cis-l,2-Dichloroethylene 

5.0 x 10 5 (1977 - captive 
production) 

NA 

NA 

T rans-1,2-Dichloroethylene 

NA 

NA 

NA 

1,1,2,2-T etrachloroethane 

NA 

NA 

NA 

1,1-DichIoroethane 

NA 

NA 

NA 

Chloral 

2.83 x 10 7 (1969) 

2.27 x 10 7 (1975) 

1.02 x 10 s (1984) 

Negligible (1972; 1975) 

Chloral Hydrate 

1.14 x 10 7 (1972 - anhydrous) 

5 .9 x 10 s (1975) 

2.83 x 10 4 (1972) 

4.8 x 10 4 (1975) 

5.41 x 10 3 (1984) 

NA 

Monochloroacetic Acid 

3.5 x 10 7 (1978) 

>6.81 x 10 3 (1982) 

1.25 x 10 7 (1978) 

1.35 x 10 7 (1982) 

Negligible (1993) 

Dichloroacetic Acid 

NA 

NA 

NA 

Trichloroacetic Acid 

>3.6 x 10* (1975) 

>2.27 x 10 3 (1976) 

3.67 x 10 6 (1984) 

8.6 x 10 6 (1984) 

Dichloro-vinyl Cysteine 

NA 

NA 

NA 


NA = Not available. 

Sources: HSDB, 1996; IARC, 1995. 


9 























INTRODUCTION 


This report summarizes currently available exposure related information about TCE, its 
metabolites, and other parent compounds that produce these same metabolites. Thus, this 
assessment is a departure from typical exposure assessment of a chemical in that it considers 
exposure to metabolites as well as parent compounds. Exposure information is summarized for 
the following 14 compounds: 

• Trichloroethylene; 

• The primary metabolites of trichloroethylene: dichloro-vinyl cysteine, chloral, 
chloral hydrate, trichloroacetic acid, dichloroacetic acid, monochloroacetic acid; 
and 

• The primary parent compounds which produce the same metabolites as 
trichloroethylene: tetrachloroethylene, methyl chloroform, 1,1,1,2- 
tetrachloroethane, cis-l,2-dichloroethylene, trans-l,2-dichloroethylene, 1,2- 
dichloroethylene, and 1,1-dichloroethane. 

Not all possible metabolites of trichloroethylene and related parent compounds were 
included in the scope of this document. The metabolites were limited to human metabolites that 
are produced in the largest quantities and are most important in producing toxic effects. The 
parent compounds were limited to those to which humans are most commonly exposed. The two 
parent compounds of most importance were trichloroethylene and tetrachloroethylene, and the 
two metabolites of most importance were trichloroacetic acid and dichloroacetic acid. These 
four compounds were given the highest priority in terms of the level of effort spent in developing 
this document. 

Figure A-l shows the parent-metabolite relationships between the compounds covered in 
this document. The actual pathways of metabolism are much more complicated than shown here 
and it should be understood that this diagram is intended only to give the reader a general 
understanding of which parent compounds lead to which metabolites. The key limitations of this 
diagram are summarized below: 

• The diagram does not include all metabolites of trichloroethylene. 

• The diagram does not include all potential parent compounds which could lead to 
the listed metabolites. For example, acetic acids are common metabolites of many 
compounds. 

• The diagram does not show the intricacies of the metabolic pathways. For 
example, interconversion can occur between some metabolites, many reactions 
include intermediate steps and the reactions can be affected by enterohepatic 
circulation and renal reabsorption. 


10 





11 


Figure A-l. Trichloroethylene, Related Parent Compounds, and Their Metabolites 















































• The diagram does not represent quantitative relationships (i.e., some metabolites 
are produced in much higher quantities than others and concepts such as half-life 
and reaction kinetics are not represented). 

This report has drawn heavily on information presented in the 1995 International Agency 
for Research on Cancer publication (IARC 1995) and profiles on several chemicals from the 
Agency for Toxic Substances and Disease Registry (ATSDR 1990, 1995, 1996a, 1997a,b). 
Additional informational sources include electronic literature searches, on-line searches of the 
Hazardous Substances Data Base, and data retrievals from the U.S. EPA Toxic Release Inventory 
(TRI). 


This report is organized in three sections. Section A includes this introduction and 
summary of the results. Section B summarizes readily available information on the physical- 
chemical properties, production and use, potential for human exposure, and exposure and 
population estimates for TCE and the other parent compounds. The final section, Section C, 
summarizes the same exposure-related information for the TCE metabolites. 

There are a number of limitations and uncertainties in this report that result primarily 
from the lack of information and that much of the data are not current, although found in current 
publications. It should be noted that monitored chemical levels presented in this report are 
primarily for the United States. Information on most metabolites is relatively sparse and is 
completely lacking for one chemical. 

Research is needed to gather data, especially to confirm current production, use, release, 
and disposal practices and study fate of the chemicals in certain media (especially groundwater 
and soils). Reliable, current monitoring data for levels in environmental media are needed to 
assess human exposures. Most of the monitoring data reported are old and based on occupational 
studies data. Additionally, the monitoring data for humans are basically for levels in blood and 
urine only. Research is needed to address monitored levels of these chemicals in other human 
tissues for the general population and populations around hazardous waste sites as well. 


12 




SECTION B. PARENT COMPOUNDS 


1.0 TRICHLOROETHYLENE 

1.1 CHEMICAL AND PHYSICAL PROPERTIES 

The information/data presented in this section and the supporting references were 
obtained from a retrieval from the Hazardous Substances Data Bank (HSDB, 1996). 

1.1.1 Nomenclature 


CAS No.: 

79-01-6 

Synonyms: 

1-chloro-2,2-dichloroethylene; ethene, trichloro-; acetylene 
trichloride, TCE. 

Trade Names: 

Chlorylea, Chlorylen, CirCosolv, Crawhaspol, Dow-Tri, 
Dukeron, Per-A-Clor, Triad, Trial, TRI-Plus M, Vitran, Perm-A- 
Chlor (and others). 


1.1.2 Formula and Molecular Weight 

Molecular Formula: C 2 HC1 3 
Molecular Weight: 131.40 

1.1.3 Chemical and Physical Properties 


Description: 

Clear, colorless, or blue mobile liquid (Remington’s Pharm. Sci., 
16th Ed., 1980); chloroform-like odor (Weast, 1986-87). 

Boiling Point: 

87° C (Weast, 1987-1988). 

Melting Point: 

-73° C (Weast, 1987-1988). 

Density: 

1.4649 @ 20° C/4° C (Merck Index, 11th Ed., 1989). 

Spectroscopy Data: 

Sadtler Ref. Number: 185 (IR, Prism); Max. Absorption: less 
than 200 nm (vapor) (Weast, 1979); Index of refraction: 1.4773 
@ 20° C/D (Weast, 1986-87); IR: 62 (Weast, 1979). 

Solubility: 

1,100 mg/1 water at 25° C (Verschueren, 1983). 

Volatility: 

Vapor Pressure: 19.9 mm Hg @ 0° C; 57.8 mm Hg @ 20° C 
(NRC, 1981). 


13 


Vapor Density: 4.53 (air = 1) (Merck Index, 1989). 

Stability: Relatively stable in air (Browning, Tox Metab Indus Solv, 1965); 

Unstable in light and moisture (Osal, 1980). 

Reactivity: Incompatible with strong caustics and alkalis; chemically-active 

metals such as barium, lithium, sodium, magnesium, titanium, 
and beryllium (NIOSH Pocket Guide Chemical Hazards, 1994). 


Octanol/Water 

Partition Coefficient: log Kow = 2.29 (Hansch, 1979). 

1.1.4 Technical Products and Impurities 

Trichloroethylene is available in the USA in high-purity, electronic USP, technical, metal 
degreasing, and extraction grades (IARC Monographs, 1972-present, V20, 1979). Commonly 
used stabilizers found in commercial trichloroethylene products include: pentanol-2 
triethanolamine, 2,2,4-trimethylpentene-l, and iso-butanol. Tetrachloroethane is a contaminant 
in commercial trichloroethylene (ARENA, 1986). Impurities found in commercial 
trichloroethylene products include: carbon tetrachloride, chloroform, 1,1,1,2-trichloroethane, and 
benzene (WHO, 1985). 

1.2 PRODUCTION AND USE 


The information/data presented in this section and the supporting references were 
obtained from a retrieval from the Hazardous Substances Data Bank (HSDB, 1996) and IARC 
(1995). 


1.2.1 Production 

U.S. Production: 

Import Volume: 
Export Volume 


(1981) 1.17 x 10 8 g (USITC, 1981); (1985) 7.72 x 10 10 g 
estimated (USITC, 1985); (1991) 1.45 x 10" g (SRI. Directory 
Chem. Producers-USA, 1992). 

(1985) 1.98 x 10 10 g (Bureau of the Census, U.S. Imports, 1985). 
(1985) 1.06 x 10 10 g (Bureau of the Census, U.S. Exports, 1985). 


1.2.2 Uses 

The major use of trichloroethylene is degreasing (IARC, 1995). About 85 percent of the 
TCE produced is used in metal cleaning. Other uses include the manufacture of organic 
chemicals; as a solvent in adhesives and paint-stripping formulations, paints, lacquers, varnishes; 
heat transfer medium-EG; in case hardening of metals; a solvent base for metal phosphatizing 
systems; and solvent in characterization test for asphalt (SRI). It was also used earlier as an 
extractant for spice oleoresins, natural fats and oils, hops and decaffeination of coffee (IARC, 


14 





1995), and a carrier solvent for the active ingredients of insecticides and fungicides, and for 
spotting fluids (WHO; Environ. Health Criteria, 1985). TCE has been replaced in the dry 
cleaning industry with tetrachloroethylene (ATSDR, 1997a). Its use as a fumigant and as an 
extractant for decaffeinating coffee has been discontinued in the U.S. (ATSDR, 1997a). Its use 
in cosmetics and drug products was also discontinued (IARC, 1995). 

1.2.3 Disposal 

Generators of waste (equal to or greater than 100 kg/month) containing this contaminant 
(EPA hazardous waste numbers U228, D040, and F002) must conform with U.S. EPA 
regulations in storage, transportation, treatment, and disposal of waste (40 CFR 240-280, 7/1/91). 
Incineration is a method of disposal, preferably after mixing with another combustible fuel. Care 
must be exercised to assure complete combustion to prevent the formation of phosgene. An acid 
scrubber is necessary to remove the halo acids produced. An alternative to disposal for 
trichloroethylene is recovery and recycling (Sittig, 1985. Handbook Toxic Hazardous Chemicals 
and Carcinogens). This compound should be susceptible to removal from wastewater by air 
stripping (U.S. EPA, 1980). 

1.3 POTENTIAL FOR HUMAN EXPOSURE 

1.3.1 Natural Occurrence 

The natural occurrence of trichloroethylene has been reported in one red microalga and in 
temperate, subtropical and tropical algae (IARC, 1995). 

1.3.2 Occupational Exposure 

Occupational exposure to TCE of workers in industries using TCE may result from 
inhalation of vapors or through dermal contact with TCE from spills. 

1.3.3 Environmental 

1.3.3.1 Environmental Releases 

Total Toxic Release Inventory (EPA, 1996) releases for years 1987 to 1994 are shown in 
Table 1-1. The receiving media are air, water, land, and for underground injection, POTW 
(Public Owned Treatment Works) transfer and other transfers. These releases are reported from 
manufacturing and processing facilities. Only certain facilities are required to report. 


15 


Table 1-1. Annual Releases of Trichloroethylene in the United States (lbs) 


Year 

Number of 
reporting 
facilities 

Fugitive air 
releases 

Stack air 
releases 

Surface 

water 

releases 

Underground 

injection 

Land 

disposal 

POTW 

transfer 

Other 

transfers 

Total 

1987 

959 

25,978,879 

29,436,952 

30,104 

18,720 

56,733 

130,178 

11,689,590 

67,341,156 

1988 

951 

26,168,126 

29,759,510 

13,801 

390 

21,186 

85,652 

6,509,867 

62,558,532 

1989 

899 

22,629,351 

27,054,328 

15,849 

390 

8,686 

31,519 

4,962,054 

54,702,177 

1990 

807 

19,030,377 

20,900,640 

14,285 

805 

12,554 

11,949 

3,879,599 

43,850,209 

1991 

724 

17,078,485 

18,860,997 

12,784 

800 

62.991 

73,195 

10,625,967 

46,715,219 

1992 

681 

15,585,757 

14,866,100 

8,606 

466 

20,726 

70,149 

9,807,719 

40,359,523 

1993 

790 

14,524,316 

15,939,964 

5,220 

460 

8,212 

42,987 

10,143,591 

40,664,750 

1994 

783 

14.788.788 

15.083.085 

1.671 

288 

4.417 

50.325 

12.307.585 

42.236.159 


Source: TRI 1996 


Air: Most of the TCE used in the U.S. is released to the atmosphere primarily from 
vapor degreasing operations by evaporation (ATSDR, 1997a). Releases to air also occur at 
treatment and disposal facilities, water treatment facilities, and landfills (ATSDR, 1997a). TCE 
has also been detected in stack emissions from the municipal and hazardous waste incineration 
(ATSDR, 1997a). TCE has been detected in the air throughout the United States. Industrial 
releases to the environment in the U.S. ranged from 55.6 million pounds in 1987 down to 29.9 
million pounds in 1994 (TRI, 1996). 

Water: TCE has been reported in rainwater, surface waters, groundwater, drinking 
water, and seawater (IARC, 1995). TCE is released to the aquatic systems from industrial 
discharges of wastewater streams (ATSDR, 1997a). It has been reported that TCE in landfill 
leachate can contaminate groundwater; TCE has been reported to be one of the most frequent 
contaminants of groundwater (ATSDR, 1997a). 

Other Media: TCE has been reported in marine sediments, marine invertebrates, marine 
mammals, foods, mother’s milk, and human urine and blood (IARC, 1995) (HSDB, 1996). 

13.3.2. Monitored Environmental Media Levels 

Air: TCE has been detected in the air throughout the United States. According to ATSDR 
(1997a), atmospheric levels are highest in areas concentrated with industry and population, and 
lower in remote and rural regions. Air levels of TCE are highly variable (fluctuate widely over 
relatively short periods of time), depending on strength of emission sources, variation of wind 
direction and velocity and other meteorological factors, rain scavenging, and 
photodecomposition. Levels of TCE measured in the ambient air at a variety of locations in the 
U.S. are shown in Table 1-2. These data were derived from studies conducted in the late 1970's 
and early 1980's. 


16 
























Table 1-2. Concentrations of Trichloroethylene in Ambient Air 



Year 

Concentration (pg/pi 3 )* 

Area 

Mean 

Range 

Rural 




Whiteface Mountain, NY 

1974 

0.5 

<0.3-1.9 

Badger Pass, CA 

1977 

0.06 

0.005-0.09 

Reese River, NV 

1977 

0.06 

0.005-0.09 

Jetmar, KS 

1978 

0.07 

0.04-0.11 

Urban and Suburban 




New Jersey 

1973-79 

9.1 

ND-97 

New York City, NY 

1974 

3.8 

0.6-5.9 

Los Angeles, CA 

1976 

1.7 

0.14-9.5 

Lake Charles, LA 

1976-78 

8.6 

0.4-11.3 

Phoenix, AZ 

1979 

2.6 

0.06-16.7 

Denver, CO 

1980 

1.07 

0.15-2.2 

St. Louis, MO 

1980 

0.6 

0.1-1.3 

Portland, OR 

1984 

1.5 

0.6-3.9 

Philadelphia, PA 

1983-84 

1.9 

1.6-2.1 


Source: IARC, 1995. * 1 ng/m ,= 0.17 ppb 

Other ambient air measurement data for TCE were obtained from the Aerometric 
Information Retrieval System (AIRS) using the AIRS Website: http://www.epa.gov/airsdata/. 
(U.S. EPA, 1999a). These data were collected from a variety of sources including State and local 
environmental agencies and cover the years 1985 to 1998. They represent about 1,200 
measurements from 25 states. The most recent data (1998) come from 115 monitors located in 
14 states. The 1998 air levels in pg/m 3 across all 115 monitors can be summarized as follows: 
range = 0.01 to 3.9; mean = 0.88, 50th percentile = 0.32 and 90th percentile = 1.76. Table 1-3 
summarizes the data by year, showing the average and number of samples. Relatively few 
samples were collected in 1985 and 1986, but each year after 1986 is represented by at least 50 
samples. The data suggest a general downward trend from about 1.5 pg/m 3 in the late 1980s to 
0.8 pg/m 3 in the late 1990s. Table 1-4 shows the monitoring data organized by land setting 
(rural, suburban, or urban) and land use (agricultural, commercial, forest, industrial, mobile, and 
residential). Urban air levels are about three times higher than rural areas. Among the land use 
categories, TCE levels are highest in commercial/industrial areas and lowest in forest areas. 

TCE ambient air concentrations in 1990 were modeled for all census tracts of the 
continental United States as part of the U.S. EPA Cumulative Exposure Project (CEP, see 
www.epa.gov/cumulativeexposure/air/air.htm). (U.S. EPA, 1999b). A variety of sources were 
used to obtain emissions data and the air modeling was done using a Gausian dispersion model. 
Table 1-5 shows the distribution of modeled TCE ambient air concentrations across the 
continental United States. The modeling suggests that 97% of the census tracts have TCE 
concentrations ranging from 0 to 1.5 pg/m 3 . The average level was estimated as 0.37 pg/m 3 and 
the maximum as 32 pg/m 3 . The averages and percentiles are better interpreted as population- 
weighted values than spatial averages because all census tracts have roughly equal populations, 
but are more variable in geographic area. Figure 1-1 is a map of the CEP-modeled TCE air 
concentrations in New Jersey. The average across all population tracts in the state is 0.5 pg/m 3 . 
The map indicates, however, that the vast majority of the state, on an area basis, has levels under 


17 









Table 1-3. Mean TCE Air Levels Across Monitors by Year 


1998 

OO 

OO 

o 

IT) 

1997 

0.74 

129 

9661 

0.65 

150 

1995 

0.78 

146 

1994 

0.95 

89 

1993 

1.12 

84 

1992 

1.37 

76 

1991 

2.86 

70 

1990 

OO 

59 

1989 

1.69 

96 

OO 

OO 

ON 

4.87 

57 

1987 

89 I 

53 

1986 

1.39 

CM 

1985 

rr 

— 


Mean Concentration 
(tig/m3) 

C 



18 
















































Inset 


Figure 1-1. Modeled TCE Levels in Air from Cumulative Exposure Project by Census Tract, 
New Jersey (gg/m 3 ) 


19 









0.5 pg/m 3 . Relatively high levels (generally 1 to 12 pg/m 3 ) were estimated for the densely 
populated areas around Camden and Newark - Paterson. The highest levels (up to 30 pg/m 3 ) were 
estimated for a few (presumably industrial) sectors within these areas. The CEP data suggest that 
this pattern (i.e., generally low TCE levels in rural areas, moderate levels in urban areas, and highest 
levels in small commercial/industrial sectors) is common across most states. The monitoring data, 
as discussed earlier, also suggest that this is the general pattern across the country. 

These modeled values should be interpreted with caution. Clearly they are not as reliable as 
measured values for specific locations. As discussed earlier, the AIRS data shows an average for 
1990 across 59 monitoring stations of 1.84 pg/m 3 . This is much higher than the national average 
from CEP of 0.37 pg/m 3 . An important difference, though, is that the CEP estimate represents all 
areas of the continental United States, whereas the 1990 AIRS data for TCE represent only 59 
monitors located in 8 states. CEP compared modeled estimates with measured values in the same 
locations and found that for most chemicals, agreement was usually within a factor of three, with 
underestimates being more common than overestimates. More variability, however, was found in 
the model-monitor comparisons for TCE than for other HAPs (hazardous air pollutants). In 
addition, the tendency for underestimation in the model observed for other HAPs was not seen for 
TCE. The TCE model-monitor comparisons can be summarized as follows: model-monitor 
comparisons were made at 57 monitoring sites, the median of the model-monitor ratios was 0.76, 
arithmetic mean ratio = 2.33, geometric mean ratio = 1.02, 53% of ratios were less than 1.0, 51% 
were within a factor of 3 (i.e. within the range of 0.33 to 3.0), 19% were less than 0.33 and 30% 
were greater than 3.0. 

Water: According to IARC (1995), the reported median concentrations of TCE in 1983-84 
were 0.5 pg/1 in industrial effluents and 0.1 pg/1 in ambient water. ATSDR (1997a) has reported 
that TCE is the most frequently reported organic contaminant in groundwater and the one present in 
the highest concentration in a summary of ground water analyses reported in 1982. It has been 
estimated that between 9 percent and 34 percent of the drinking water supply sources tested in the 
U.S. may have some trichloroethylene contamination. This estimate is based on available Federal 
and State surveys (ATSDR, 1997a). Results from an analysis of the EPA STORET Data Base 
(1980-1982) showed that TCE was detected in 28 percent of 9,295 surface water reporting stations 
nationwide (ATSDR, 1997a). Levels of TCE found in rainwater, groundwater, and drinking water 
are shown in Table 1-6. 

More recently, the U.S. EPA Office of Ground Water and Drinking Water reported that 
most water supplies are in compliance with the maximum contaminant level [maximum 
contaminant level (MCL), 5 pg/L] and that only 407 samples out of many thousands taken from 
community and other water supplies throughout the country over the past 11 years (1987-1997) 
have exceeded the MCL limit for TCE (U.S. EPA, 1998). 

TCE concentrations in ground water have been measured extensively in California. The data 
were derived from a survey of large water utilities (i.e., utilities with more than 200 service connec¬ 
tions). The survey was conducted by the California Department of Health Services (DHS, 1986). 
From January 1984 through December 1985,.wells in 819 water systems were sampled for organic 


20 



chemical contamination. The water systems use a total of 5,550 wells, 2,947 of which were 
sampled. TCE was found in 187 wells at concentrations up to 440 (ig/L, with a median 

Table 1-6. Concentrations of Trichloroethylene in Water 


Water Type 

Location 

Year 

Mean 

Median 

Range 

Number of Samples 

Ref. 

Industrial 

U.S. 

83 


0.5 


NR 

IARC, 1995 

Effluent 








Surface Waters 

U.S. 

83 


0.1 


NR 

IARC, 1995 

Rainwater 

Portland, OR 

84 

0.006 


0.002-0.02 

NR 

Ligocki, et.al, 1985 

Groundwater 

MN 

83 



0.2-144 

NR 

Sabel, et.al, 1984 


NJ 

76 



<1530 

NR 

Burmaster, et. al. ‘82 


NY 

80 



<3800 

NR 

Burmaster, et. al. ‘82 


PA 

80 



<27300 

NR 

Burmaster, et. al. ‘82 


MA 

76 



<900 

NR 

Burmaster, et. al. ‘82 


AZ 




8.9-29 

NR 

IARC, 1995 

Drinking water 

U.S. 

76 



0.2-49 


IARC, 1995 


U.S 

77 



0-53 


IARC, 1995 


U.S. 

78 



0.5-210 


IARC, 1995 


MA 

84 



max. 267 


IARC, 1995 


NJ 

1 

OO 

23.4 


max. 67 

1130 

Cohn, et.al., 1994 


CA 

85 



8-12 

486 

EPA, 1987 


CA 

84 

66 



486 

EPA, 1987 


NC 

84 

5 



48 

EPA, 1987 


ND 

84 

5 



48 

EPA, 1987 


NR - Not Reported 


concentration of 3.0 pg/L. Generally, the most contaminated wells and the wells with the highest 
concentrations were found in the heavily urbanized areas of the state. Los Angeles County 
registered the greatest number of contaminated wells (149). 

Other Media: Levels of TCE were found in the sediment and marine animal tissue 
collected in 1980-81 near the discharge zone of a Los Angeles County waste treatment plant. 
Concentrations were 17 pg/1 in the effluent, <0.5 pg/kg in dry weight in sediment, and 0.3-7 
pg/kg wet weight in various marine animal tissue (IARC, 1995). TCE has also been found in 
foods in the U.S. and the United Kingdom. The average concentrations of TCE in food in the 
U.S. were the following (IARC, 1995): 

• 0.9 pg/kg in grain-based foods; 

• 1.8 pg/kg in table-ready foods; 

• 73.6 pg/kg in butter and margarine; 

• 0.5 pg/kg in peanut butter; 

• 3.0 pg/kg in ready-to-eat cereals; 

• 1.3 pg/kg in highly processed foods; and 

• 3.8 pg/kg in cheese products. 


Biological Monitoring: Biological monitoring studies have detected TCE in human 
blood and urine in the U.S. and other countries such as Croatia, China, Switzerland, and 


21 
















Germany (IARC, 1995). Concentrations of TCE in persons exposed through occupational 
degreasing operations were most likely to have detectable levels (IARC, 1995). In 1982, eight of 
eight human breastmilk samples from four U.S. urban areas had detectable levels of TCE. The 
levels of TCE detected, however, were not specified (HSDB, 1996; ATSDR, 1997a). 

The Third National Health and Nutrition Examination Survey (NHANES III) examined 
TCE concentrations in blood in 677 non-occupationally exposed individuals drawn from the 
general U.S. population who were selected on the basis of age, race, gender and region of 
residence (IARC, 1995 and Ashley et al., 1994). The samples were collected during 1988 to 
1994. TCE levels in whole blood were below the detection limit of 0.01 |ig/l for about 90% of 
the people sampled (Table 1-7). Assuming that nondetects equal half of the detection limit, the 
mean concentration was about 0.017 pg/1. 

1.3.3.3 Environmental Fate and Transport 

1.3.3.3.1 Summary’ 

The summary is based on the data presented in the subsequent fate and transport 
subsections. 

Fate in Terrestrial Environments: The dominant fate of trichloroethylene released to 
surface soils is volatilization. Because of its moderate to high mobility in soils, trichloroethylene 
introduced into soil (e.g., landfills) has the potential to migrate through the soil into groundwater. 
The relatively frequent detection of trichloroethylene in groundwater confirms the mobility of 
trichloroethylene. Biodegradation in soil and groundwater may occur at a relatively slow rate 
(half-lives on the order of months to years) (Howard et al., 1991). 

Fate in the Atmosphere: In the atmosphere, trichloroethylene is expected to be present 
primarily in the vapor phase rather than sorbed to particulates because of its high vapor pressure. 
Some removal by scavenging during wet precipitation is expected because of the moderate 
solubility of trichloroethylene in water (1.1 g/L). The major degradation process affecting vapor 
phase trichloroethylene is photo-oxidation by hydroxyl radicals (half-life on the order of 1 to 11 
days) (HSDB, 1996). 

Fate in Aquatic Environments: The dominant fate of trichloroethylene released to 
surface waters is volatilization (predicted half-life of minutes to hours). Bioconcentration, 
biodegradation, and sorption to sediments and suspended solids are not thought to be significant 
(HSDB, 1996). 

Table 1-7. TCE Levels in Whole Blood by Population Percentile* 


Percentiles 

10 

20 

30 

40 

50 

60 

70 

80 

90 

Concentration 

(Pg/l) 

0.005 

0.005 

0.005 

0.005 

0.005 

0.005 

0.005 

0.005 

0.012 


* Nondetects assumed equal to half the detection limit (0.01 ^g/L). 
Data from IARC (IARC, 1995) and Ashley (Ashley, 1994) 


22 
















1.3.3.3.2 Transport and Partitioning 


Soil Adsorption/Mobility: K oc s ranging from 30 to 150 have reported in studies with 
various soil types indicate that trichloroethylene should exhibit moderate to high mobility in soil. 
The mobility of trichloroethylene in soil has been confirmed in soil column studies and river 
bank infiltration studies (HSDB, 1996). 

Volatilization: The dominant removal mechanism for trichloroethylene in surface waters 
is volatilization. The half-life will depend on wind and mixing conditions and is estimated to 
range from several minutes to hours in rivers, lakes, and ponds based on laboratory experiments 
and field studies. Because of its high vapor pressure (73 torr at 25 degrees C) and relatively low 
soil adsorption coefficient (30 to 150), trichloroethylene is expected to volatilize from soil 
surfaces and also from suspended particulate matter in the atmosphere (HSDB, 1996). 

Bioconcentration: Bioconcentration factors of 17 to 39 have been reported in bluegill 
sunfish and rainbow trout. Marine monitoring data suggest BCFs of 2 to 25. Therefore, 
bioconcentration in aquatic organisms should not be significant and there is little potential for 
biomagnification in the food chain (HSDB, 1996). 

1.3.3.3.3 Transformation and Degradation Processes 

Biodegradation: Based on limited acclimated soil screening test data, trichloroethylene 
undergoes aerobic biodegradation at a very slow rate with a half-life estimated at 6 months to a 
year. Slow degradation under anaerobic conditions is expected (half-life of months to years) 
based on the results of limited anaerobic sediment studies (Howard et al., 1991). 

Photodegradation: Photolysis in the atmosphere or in aquatic environments is expected 
to proceed very slowly, if at all. Trichloroethylene does not absorb UV light at wavelengths of 
less than 290 nm and thus will not directly photolyze. Based on measured rate data for the vapor 
phase photo-oxidation reaction with hydroxyl radicals, the estimated half-life of trichloroethylene 
in the atmosphere is on the order of 1 to 11 days with production of phosgene, dichloroacetyl 
chloride, and formyl chloride. Under smog conditions, degradation is more rapid (half-life on the 
order of hours) (HSDB, 1996; Howard et al., 1991). 

Hydrolysis: Trichloroethylene is not hydrolyzed under normal environmental conditions. 
However, slow photo-oxidation in water (half-life of 10.7 months) has been reported (HSDB, 
1996; Howard et al., 1991) 

1.4 HUMAN EXPOSURE AND POPULATION ESTIMATES 
1.4.1 General U.S. Population 

Because of the pervasiveness of TCE in the environment, most people are exposed to it 
through ingestion of drinking water, inhalation of ambient air, or ingestion of food (ATSDR, 
1995a). Contamination of drinking water with TCE varies according to location and with the 
drinking water source (whether source is surface water or groundwater). TCE readily volatilizes 
from water and inhalation of indoor air may be a major route of exposure in homes with 


23 




contaminated water supply (ATSDR, 1997a). Available data indicate that for most people, 
dermal exposure is not an important route of exposure (ATSDR, 1997a). 

The 1998 AIRS monitoring data indicate a mean outdoor air level of 0.88 pg/m 3 . Using 
this value and an inhalation rate of 20 m 3 air/day yields an exposure estimate of 18 pg/day. This 
is consistent with ATSDR (ATSDR, 1997a), which reported an average daily air intake for the 
general population of 11 to 33 pg/day The California survey of large water utilities in 1984 found 
a median concentration of 3.0 pg/L (DHS, 1986). Using this value and a 2 L/day water 
consumption rate yields an estimate of 6 pg/day. This is consistent with ATSDR (ATSDR, 
1997a) which reported an average daily water intake for the general population of 2 to 20 pg/day. 

The use of ambient air data to estimate inhalation exposure does not account for possible 
differences between contaminant levels in indoor vs. outdoor air. TCE readily volatilizes from 
water and indoor inhalation exposure may be comparable or greater than ingestion exposures in 
homes where the water supply contains TCE (ATSDR, 1997a, Andelman, et.al., 1985, Giardino, 
et.al., 1992, Andelman, et.al., 1986a, Andelman, et.al., 1986b). For example, in two homes using 
well water with TCE levels averaging 22 to 128 pg/L, the TCE levels in bathroom air ranged 
from <0.5 to 40 mg/nT when the shower was run less than 30 minutes (Andelman et al., 1985). 

In one study, the transfer of TCE from shower water to air had a mean efficiency of 61% 
(independent of water temperature); it was concluded that a 10-minute shower in TCE- 
contaminated water could result in a daily inhalation exposure comparable to that expected from 
drinking TCE-contaminated tap water (ATSDR, 1997a). Indoor use of TCE containing products 
can also contribute to exposures. Wallace et al. (Wallace, et.al., 1985) concluded that indoor air 
contributes more to overall TCE exposure than outdoor air. This was based on monitoring of 
expired breath of 190 people in New Jersey. This is also indicated in the TEAM (Total 
Exposure Assessment Methodology) Study (U.S. EPA, 1987), which shows, for example, that 
the ratio of the indoor to outdoor TCE concentration for Greensboro, NC was about 5:1. 
Accordingly, ambient air-based exposure estimates probably under represent total inhalation 
exposures. 

TCE in bathing water can also cause dermal exposure. A modeling study has suggested 
that a significant fraction of the total dose associated with exposure to volatile organics in 
drinking water results from dermal absorption (Brown, et.al., 1984). 

Pharmacokinetic modeling can be used to gain further understanding of general 
population exposure. Clewell et al. (Clewell, et.al., 1995) developed a physiologically based 
pharmacokinetic model for TCE that can be used to estimate the long-term average inhaled air 
concentration that would result in a measured blood concentration, assuming no other TCE 
exposure. The model can also estimate the long-term average ingested dose that would result in 
a measured blood concentration, assuming no other TCE exposure. This dose can be converted 
to a TCE water concentration assuming an ingestion rate such as 2 L/day. For each of these 
exposure scenarios, the model also provides the corresponding concentrations of trichloroacetic 
acid (TCA) and dichloroacetic acid (DCA) in blood and the amount of TCE metabolized per day. 
This model was applied to the range of TCE levels in blood as measured in NHANES III. Table 
1-8 shows the resulting exposure estimates corresponding to the range of TCE blood levels. The 
TCE environmental concentrations modeled from blood levels exceeded the range of measured 
values for air and water: modeled mean concentration in drinking water was 59.5 pg/L (measured 
range was trace to 50 pg/L) and the modeled mean air concentration was 4.2 pg/m 3 (measured 


24 







range was for 0.01 to 3.9 pg/nf). This implies that neither inhalation nor water ingestion 
dominate exposure; rather both contribute to the total exposure. Exposure estimates derived 
from blood cannot distinguish among exposure routes and sources. It is generally believed that 
TCE exposure occurs primarily via water consumption and air inhalation, but it is impossible to 
use the blood data to directly estimate how much of the total exposure is attributable to each. A 
wide range of combinations of exposures from air and water could have produced the measured 
blood levels. As noted earlier, most water supplies have TCE levels under the MCL of 5 pg/L. 
The modeling suggests that exposure at the MCL would correspond to a very low blood level. 
This implies that the TCE exposure via the air and other nonwater pathways may generally be 
more important than water ingestion. Table 1-8 provides the modeled exposure estimates 
corresponding to a range of blood levels, and Table 1-9 shows a comparison of measured and 
modeled TCE concentrations in air and drinking water. 

1.4.1.1 Extent of General Population Exposure 

Because of the pervasiveness of TCE in the environment, most people are likely to have 
some exposure via one or more of the following pathways: ingestion of drinking water, 
inhalation of ambient air, or ingestion of food (ATSDR, 1995a). As noted earlier, the NHANES 
survey suggests that about 10% of the population has detectable levels of TCE in blood. The 
exposures in these individuals may be higher than those in others in the general population as a 
result of a number of factors. As discussed below, some occupations and the use of certain 
consumer products can cause increased TCE exposure via inhalation. In addition, some 
members of the general population may have increased TCE exposure via their drinking water. 
The extent of TCE exposure via drinking water is difficult to estimate, but the following 
discussion provide some perspective on this issue. 


Table 1-8. Modeled Exposure Estimates for TCE 



Air concentration 
(pg/m 3 ) 

Ingested dose 
(pg/kg-day) 

Water concentration 
(Hg/L) 

10th percentile blood level 
(0.005 pg/L) 

1.25 

0.5 

17.5 

90th percentile blood level 
(0.012 pg/L) 

3.0 

1.2 

42.0 

Mean blood level (0.017 

■Md_ 

4.3 

1.7 

59.5 


Table 1-9. Comparison of Measured and Modeled TCE Concentrations 


‘ V- . ' . ' ' '' • 

Measured Range 

Modeled Mean 

Air 

0.0005 to 16 ug/m 3 

4.58 pg/m 3 

Drinking Water 

trace to 50 pg/L 

59.5 pg/1 


25 
















TCE is the most frequently reported organic contaminant in ground water (ATSDR, 
1997a), 93% of the public water systems in the United States obtain water from groundwater 
(U.S. EPA, 1995) and between 9% and 34% of the drinking water supply sources tested in the 
United States may have some TCE contamination (ATSDR, 1997a). Although commonly 
detected in water supplies, the levels are generally low since, as discussed earlier, MCL 
violations for TCE in public water supplies are relatively rare for any extended period (U.S. EPA, 
1998). Private wells, however, are often not closely monitored and if located near TCE 
disposal/contamination sites where leaching occurs, may have undetected contamination levels. 
About 10% of Americans (27 million people) obtain water from sources other than public water 
systems, primarily private wells (U.S. EPA, 1995). TCE is a common contaminant at Superfund 
sites. It has been identified in at least 861 sites of the 1,428 hazardous waste sites proposed for 
inclusion on the EPA National Priorities List (NPL) (See Figure 1-2. ATSDR, 1997a). Studies 
have shown that many people live near these sites: 41 million people live less than 4 miles from 
one or more of the nation's NPL sites, and on average 3,325 people live within 1 mile of any 
given NPL site (ATSDR, 1996b). Thus, although exact estimates cannot be made, many people 
are probably exposed to TCE via drinking water from private wells. It is not known how often 
such exposures would be above the MCL. 

Some members of the general population may have elevated TCE exposures. ATSDR 
(ATSDR, 1997a) has reported that TCE exposures may be elevated for people living near waste 
facilities where TCE may be released, residents of some urban or industrialized areas, people 
exposed at work (discussed further below) and individuals using certain products (also discussed 
further below). Because TCE has been detected in breast milk samples of the general population, 
infants who ingest breast milk may be exposed. Also, since TCE can be present in soil, children 
may be exposed through activities such as playing in or ingesting soil. 

1.4.2 Occupational Exposure 

Occupational exposure to TCE in the U.S. has been identified in various degreasing 
operations, silk screening, taxidermy, and electronic cleaning (IARC, 1995). The major use of 
trichloroethylene is for metal cleaning or degreasing (IARC, 1995). Degreasing is used to 
remove oils, greases, waxes, tars, and moisture before galvanizing, electroplating, painting, 
anodizing, and coating. The five primary industrial groups are: furniture and fixtures; electronic 
and electric equipment; transport equipment; fabricated metal products; and miscellaneous 
manufacturing industries (IARC, 1995). Additionally, TCE is used in the manufacture of 
plastics, appliances, jewelry, plumbing fixtures, automobile, textiles, paper, and glass (IARC, 
1995). NIOSH conducted a survey of various industries from 1981 to 1983 and estimated that 
approximately 401,000 U.S. employees in 23,225 plants in the U.S. are potentially exposed to 
TCE (IARC, 1995; ATSDR, 1997a). The majority of published worker exposure data are for 
degreasing operations; time weighted average (TWA) concentrations from personal monitoring 
ranged from 6,535-27,775 pg/m J (1.2 to 5.1 ppm) at individual industrial sites where TCE was 
used (ATSDR, 1997a). 

According to ATSDR (1997a), workers, especially in the vapor degreasing industry, are 
exposed to the highest levels of TCE through inhalation. These workers may be exposed to 


26 




levels ranging from approximately 5,446-544,600 pg/m 3 (1 to 100 ppm), based on monitoring 
survey (ATSDR, 1997a). 

1.4.3 Consumer Exposure 

Consumer products reported to contain TCE include wood stains, varnishes, and finishes; 
lubricants; adhesives; typewriter correction fluids; paint removers; and cleaners (ATSDR, 

1997a). Use of TCE has been discontinued in some consumer products (i.e., as an inhalation 
anesthetic, fumigant, and an extractant for decaffeinating coffee) (ATSDR, 1997a). 

1.5 CHAPTER SUMMARY 

Table 1-10 summarizes the findings of TCE. 


27 



FREQUENCY )l I It I I 1 TO 15 SITES 16 TO 33 SITES 

HHHMBffl l 57 TO 72 SITES B3 TO 92 SITES 



Figure 1-2. Frequency of NPL Sites with Trichloroethylene Contamination (Source: ATSDR, 
1997a) 













































































































































































































































































































































































































































































































Table 1-10. Trichloroethylene Summary 



Estimates 

Support 

Uses 

Metal cleaning and degreasing; many other 
solvent applications 

Well documented in numerous studies, 
recent information 

Production 

1.45 x 10 x kg/yr 

1991 data 

Releases 

All media - 42 million lb/yr (mostly to ai) in 
1994 

TRI (U.S. EPA, 1996) is primary source, so 
current but uncertain due to self reporting 
and exemptions 

Properties/Fate 

Volatile, water soluble, stable in air, no 
significant bio-degradation or bio¬ 
concentration 

Well documented in numerous studies, 
recent information 

Media Levels 

- Air: mean = 0.88 pg/m 3 

- Drinking water: 2-7 pg/L 

- Groundwater: median = 3 pg/L 

- Human blood: mean = 0.017 pg/L 

- Some data on food, human milk, and 
other tissues 

- Air data is from 1998 survey of 115 
monitors in 14 states 

- Based on extensive data from public 
water systems which routinely monitor 
for TCE, private systems generally do not 
monitor for TCE and levels not well 
established 

- Groundwater estimate from 1985 survey 
of 819 water systems in CA 

- Blood data collected from 1988 to 1994 
from 677 individuals 

- n’s and dates for other data unclear, but 
appear very limited 

General Population 
Exposure 

- Inhalation: 11-33 pg/d (urban) 

- Water ingestion: 2-20 pg/d 

- Food exposure possible but probably low 

- Inhalation and ingestion estimates based 
on very limited monitoring data (see 
above) 

- Insufficient food data for reliable 
estimates of exposure 

Special Population 
Exposures 

- Nursing infants 

- Workers in production plants or 
degreasing operations: 1-100 ppm 

- Human milk data insufficient for 
estimating exposure 

- Worker data based on several recent 
surveys 


29 













2.0 TETRACHLOROETHYLENE (PERCHLOROETHYLENE) 


2.1 CHEMICAL AND PHYSICAL PROPERTIES 

The information/data presented in this section and the supporting references were 
obtained from a retrieval from the Hazardous Substances Data Bank (HSDB, 1996). 

2.1.1 Nomenclature 


CAS No.: 

127-18-4 

Synonyms: 

1,1,2,2-tetrachloroethylene; ethene, tetrachloro-, 
perchloroethylene; tetrachloroethene; PCE. 


Trade Names: ENT 1; 860; Perclene; Persec; Antisal 1; Dow-Per; Perchlor; Perklone. 

2.1.2 Formula and Molecular Weight 

Molecular Formula: C 2 C1 4 

Molecular Weight: 165.83 

2.1.3 Chemical and Physical Properties 

Description: Colorless liquid, ether-like or chloroform-like odor (Merck Index, 10th 
Ed., 1983). 

Boiling Point: 121° C @ 760 mm Hg (Weast. Hdbk. Chem. & Phys., 68th Ed., 1987-88). 


Melting Point: 

-19° C (Weast. Hdbk. Chem. & Phys., 68th Ed., 1987-88). 

Density: 

1.6227 at 20° C/4° C (Weast. Hdbk. Chem. & Phys., 68th Ed., 
1987-88). 

Spectroscopy 

Data: 

Sadtler Ref. Number: 237 (IR, prism); 79 (IR, grating) (Weast. 
Hdbk.Chem. & Phys., 60th Ed., 1979). Index of refraction: 1.5053 
@ 20° C/D (Weast. Hdbk. Chem. & Phys., 68th Ed., 1987-88). IR: 
4786 (Coblentz Society Spectral Collection), Mass: 1053 (Atlas of 
Mass Spectral Collection) 

Solubility: 

Soluble in water, 0.15 g/100 ml @ 25°C (IARC Monographs) 
(1972-present) 1979. Miscible with alcohol, ether, chloroform, 
benzene (Merck Index, 10th Ed., 1983). 

Volatility: 

Vapor Pressure - 18.47 mm Hg at 25°C (Riddick, J.A., et al. (1986) 
Organic Solvents: Physical Properties and Methods of Purification). 


30 






Vapor Density -5.7 (air = 1) (Browning Tox. & Metab. Indus. Solv., 
1965). 


Stability: Rapidly deteriorates in warm climates (Goodman, 1975); 

tetrachloroethylene is stable up to 500°C in the absence of catalysts, 
moisture, and oxygen (WHO, Environ. Health Criteria, 1984). 

Reactivity: Reacts with metals to form explosive mixtures; sodium hydroxide, 

possible explosion (ITII. Tox. & Hazard Indus. Chem. Safety Manual, 
1982). Incompatible with chemically active metals, such as barium, 
lithium, and beryllium (NIOSH Pocket Guide, 1985). 


Octanol/Water 

Partition 

Coefficient: log Kow = 3.40 (Hansch C., Leo A.J., 1985, Medchem Project Issue 

No. 26) 


2.1.4 Technical Products and Impurities 

Tetrachloroethylene is available in the USA in the following grades: purified, technical, 
USP, spectrophotometric, and dry-cleaning. The technical and dry-cleaning grades both meet 
specifications for technical grade and differ only in the amount of stabilizer added to prevent 
decomposition. Stabilizers include amines or mixtures of epoxides and esters. Typical analysis 
of the commercial grade is nonvolatile residue, 0.0003%; free chlorine, none; moisture, no cloud 
at -5°C. USP grade contains not less than 99.0% and no more than 99.5% tetrachloroethylene, 
the remainder consisting of ethanol (IARC Monographs, 1972-Present V20 492, 1979). PCE is 
also available in the United States in veterinary preparation (Nema Worm Capsules) (AMA Drug 
Eval., 1986). 


2.2 PRODUCTION AND USE 


The information/data presented in this section and the supporting references were 
obtained from a retrieval from the Hazardous Substances Data Bank (HSDB, 1996). 

2.2.1 Production 

U.S. Production: (1985) 3.08 x 10 11 g; (1986) 1.84 x 10 11 g; (1989) 2.14 x 10 n g; 
(1990) 1.6 x 10 n g; (1991) 1.08 x 10" g; (1992) 1.12 x 10 n g; (1993) 1.23 x 
10 11 g (ATSDR, 1995b; HSDB, 1996). 

Import volumes: (1982) 1.70 x 10 10 g; (1985) 6.36 x 10 10 g; (1986) 8.3 x 10 7 g 
(Bureau of the Census, U.S. Imports for Consumption and General Imports, 1985; 
1986). 

Export volumes: (1983) 2.47 x 10 10 g (SRI); (1985) 9.84 x 10 9 g (Bureau of the 
Census, U.S. Exports, 1985). 


31 


2.2.2 Uses 


The three major uses of tetrachloroethylene in the U.S. are textile dry-cleaning; 
processing and finishing in both cold cleaning and vapor degreasing of metals; and as a chemical 
intermediate in the synthesis of fluorocarbon 113, 114, 115, and 116. However, because of an 
international agreement to protect against ozone layer depletion, this latter use is being phased 
out (IARC, 1995). Additionally, PCE is used as a heat-exchange fluid; a scouring, sizing, and 
desizing agent; a carrier solvent for fabric dyes and finishes; a water repellant in textile 
manufacture; a component of aerosol laundry-treatment products; a solvent for silicones; 
insulating fluid and cooling gas in electric transformers (SRI); and a solvent in typewriter 
correction fluids (IARC, 1995). Other reported uses are extractant in the pharmaceutical 
industry; a pesticide; and a solvent for adhesive formulations, printing inks, leather treatments; 
and paper coatings. It has also been reported to be used as an anthelminthic in the treatment of 
hookworm and some trematode infestations (IARC, 1995) although it has been replaced now 
with other less toxic and easier-to-administer compounds. 

The current end-use pattern for PCE is estimated to be 55% for chemical intermediates, 
25% for metal cleaning and vapor degreasing, 15% for dry cleaning and textile processing, and 
5% for other unspecified uses (ATSDR, 1997b). 

2.2.3 Disposal 

Incineration at a temperature greater than 450°C is a method of disposal, preferably after 
mixing with another combustible fuel. Care must be exercised to assure complete combustion to 
prevent the formation of phosgene. An acid scrubber is necessary to remove the halo acids that 
are produced (ATSDR, 1997b). PCE may be disposed of in landfills by adsorbing it in 
vermiculite, dry sand, earth, or a similar material and disposing in a secured sanitary landfill 
(ATSDR, 1997b). According to HSDB (1996), an environmental regulatory agency should be 
consulted prior to implementing land disposal of waste containing PCE. The HSDB database 
presents numerous disposal practice precautions for carcinogens from the IARC 1979 Scientific 
Publication No. 33. 

2.3 POTENTIAL FOR HUMAN EXPOSURE 

2.3.1 Natural Occurrence 

The natural production of PCE in temperate, subtropical, and tropical algae, and in one 
red microalga has been reported (IARC, 1995). 

2.3.2 Occupational 

There is considerable potential for exposure to PCE (dermal and inhalation) during its use 
in degreasing and dry cleaning operations (IARC, 1995). Other occupational areas where 
exposures may occur are urethane foam, automotive brake, and rubber molding manufacture; 
motion picture film processing; taxidermy; electroplating; and graphic arts. 


32 






2.3.3 Environmental 


PCE is released to the environment through industrial emissions, from building products 
and consumer products. Releases are primarily to the atmosphere, but there are additional 
releases to surface water and land in sewage sludges, other liquids, and solid wastes. Because of 
the high vapor pressure, PCE is volatilized to the atmosphere from these sources (ATSDR, 
1997b). The Toxic Release Inventory (TRI) industrial release data for PCE releases to air, water, 
land, and other media from manufacturing facilities are presented in Table 2-1. The number of 
reporting facilities and the total releases per year are also shown in Table 2-1. 

2.3.3.1 Environmental Releases 

Air: Levels of PCE in air have been reported in numerous studies, both in the U.S. and 
worldwide. PCE has been found in ambient air, especially in the near vicinity of dry cleaning 
operations. The TRI emission estimate for total PCE industrial emissions to the atmosphere was 
32.9 million pounds in 1987; 17 million pounds in 1991; and 5.2 million pounds in 1994 (TRI, 
1996). 


Water: PCE has been detected in rainwater, surface water, drinking water, and seawater. 
According to TRI, releases to surface water totaled 161,000 pounds in 1987; 7,448 pounds in 
1991; and down to 3,872 pounds in 1994 (TRI, 1996). 

Other Media: Levels of PCE have been reported in foods, marine invertebrates, fish, 
waterbirds, marine mammals, marine sediments, and human blood, urine, breast milk, and tissue 
(I ARC, 1995; ATSDR, 1997b; HSDB 1996). TRI estimates of releases for land disposal were 
618,026 pounds in 1993 down to 4,349 pounds in 1994 (TRI, 1996). 


Table 2-1. Releases of Tetrachloroethylene (lbs) 


Year 

Number of 

Reporting 

Facilities 

Fugitive Air 
Releases 

Stack Air 
Releases 

Surface 

Water 

Release 

Underground 

Injection 

Land 

Disposal 

POTW 

Transfer 

Other Transfers 

Total 

1987 

715 

15,628,341 

17,273,459 

160,921 

354,000 

5,220 

468,295 

9,155,484 

43,046,435 

1988 

746 

16,336,282 

19,786,265 

33,314 

72,250 

82,144 

558,691 

5,582,693 

42,452,385 

1989 

732 

12,187,707 

15,753,023 

53,940 

50,000 

10,791 

467,181 

4,356,193 

32,879,567 

1990 

666 

9,351,150 

13,597,042 

21,510 

11,012 

1,260 

450,922 

4,548,481 

27,982.043 

1991 

577 

6,669,093 

10,339,157 

7.448 

14,000 

23,309 

234,642 

16,290,418 

33,578,644 

1992 

518 

5,305,402 

7,389,816 

10,317 

12,780 

9,354 

111,517 

11,011,874 

23,851,578 

1993 

490 

4,538,411 

6,634,275 

10,152 

15,041 

618,026 

111,002 

9.564,687 

21,492,084 

1994 

459 

4,671,751 

5,530,378 

3,872 

4,051 

4,349 

62,053 

10,411,056 

20,687,969 


Source: TRI, 1996. 


33 




















23.3.2 Monitored Environmental Media Levels 


Air: Measured levels of PCE in air in rural, urban, and suburban locations in the U.S. are 
shown in Table 2-2. 


Water: Measurements of PCE in surface waters, groundwater, and drinking water in 
U.S. locations are shown in Table 2-3. 


Other Media: PCE was reported as a contaminant of cosmetic products (0.3-400 pg/1) 
and cough mixtures (0.2-97.1 pg/1) (IARC, 1995). PCE has been detected in blood and urine of 
occupationally exposed persons. It has also been reported in 7 of 42 breast milk samples from 
the general population in 4 urban areas of the U.S. (IARC, 1995; HSDB, 1996). PCE was 
detected at 1.4 - 5.7 ppt in rain/snow in California (HSDB, 1996). Levels found in food included 
(ATSDR, 1997b; HSDB, 1996): 

• Crab apple jelly - 2.5 pg/kg 

• Grape jelly - 1.6 pg/kg 

• Dairy products - 0.3 - 13 pg/kg 

• Oils and fats - 0.01 - 7 pg/kg 

• Beverages (canned fruit drinks, instant coffee, tea) - 2 - 3 pg/kg 

• Fruits and vegetables (potatoes, apples, pears, tomatoes) - 0.7 - 2 pg/kg 

• Grain-based products (wheat, com, oats, com grits, com meal) - 1.8 - 2.5 pg/kg 


Table 2-2. Concentrations of Tetrachloroethylene in Ambient Air 


Area 

Concentration (ng/m 3 )* 

Mean 

Range 

Rural 



Southern Washington, USA 

136 


Rural California, USA 

210 


Central Michigan. USA 


200-300 

USA, 577 sites 

1,085 


Urban and Suburban 



New York City, NY, USA 

9,017 

1,085-71,936 

Houston, TX, USA 

2,644 

<678-30,510 

Detroit, MI, USA 

3,119 

678-14,916 

Los Angeles, CA, USA 

10,034 

1,180-14,001 

Phoenix, AZ, USA 

6,739 

875-25,066 

Oakland, CA, USA 

2,054 

359-9,831 

San Diego, CA, USA 

1,831 


San Francisco, CA, USA 

1,559 


Sacramento, CA, USA 

475 



Source: IARC, 1995. * 1 ng/m 3 =0.00014 ppb 


34 












Table 2-3. Concentrations of Tetrachloroethylene in Water 



Concentration (pg/L) 

Area 

Mean 

Range 

Surface Waters: 



Seawater 



Eastern Pacific 


0.0001-0.0021 

North Atlantic 


0.00012-0.0008 

Rainwater 



Los Angels, CA, 1982 

0.021 


La Jolla, CA 

0.006 


Portland, OR 


0.0008-0.009 

Germany 

0.08 


Rivers 



USA, five states, surface water (14% of samples 


max. 21 

positive) 



Drinkine Water 



New Jersey, USA, 1981-83 

0.4 


New Jersey, USA 

7.7 


Woburn, MA, USA 


max. 14 



66-212 

Groundwater: 



USA, CA, 945 Water supplies 


max. 0.58-69 

USA, five sites, 28% of samples positive 


max. 1500 


Source: I ARC, 1995. 


Levels of PCE detected in margarine from several supermarkets in the Washington, D.C., 
area were >50 ppm in 10.7 percent of the products sampled. The highest levels, ranging from 
500 to 5,000 ppb, were found in samples from a store located near a dry cleaning operation 
(ATSDR, 1995b). The concentrations were highest on the ends of the margarine stick and 
decreased towards the middle, suggesting that contamination occurred after manufacturing rather 
than during the manufacturing process (ATSDR, 1997b). 

Biological Monitoring: The Third National Health and Nutrition Examination Survey 
(NHANES III) examined perchloroethylene concentrations in blood in 590 non-occupationally 
exposed individuals (I ARC, 1995 and Ashley et ah, 1994). This study involved persons in the 
general U.S. population who were selected on the basis of age, race, gender and region of 
residence. The samples were collected during 1988 to 1994. As shown in Table 2-4 below, the 
tetrachloroethylene levels in whole blood span over a wide range with a mean concentration of 
0.19 pg/1. This result is also shown on Figure 2-1. 


35 












0.4 



10 20 30 40 50 60 70 80 90 

Population Percentile 


Source: NHANES III (Ashley, D., 1997, CDC). N=590 

Figure 2-1. Concentration of Tetrachloroethylene in Blood at Selected Population Percentiles 


36 















Table 2-4. Tetrachloroethylene Levels in Whole Blood by Population Percentile* 


Percentiles 

10 

20 

30 

40 

50 

60 

70 

80 

90 

Concentration (|Jg/l) 

0.015 

0.015 

0.035 

0.049 

0.063 

0.086 

0.120 

0.180 

0.35 


* detection limit = 0.03 ng/L 

Source: Personal communication from David Ashley, Center for Disease Control. 


Clewell (personal communication to J. Schaum, 1997) applied the NHANES III blood 
data for tetrachloroethylene to a physiologically based pharmacokinetic model (described in 
Gearhart et al., 1993) to estimate the following quantities: 

• The long term average inhaled air concentration which would result in the 
measured blood concentration, assuming no other perchloroethylene exposure. 

• The long term average ingested dose which would result in the measured blood 
concentration, assuming no other perchloroethylene exposure. This dose was 
converted to a perchloroethylene water concentration assuming an ingestion rate 
of 2 1/day. 

• For each of these exposure scenarios, the model also provides the corresponding 
concentrations of TCA and DCA in blood and the amount of perchloroethylene 
metabolized per day. 

This model (Gearhart et al., 1993) includes 30 to 40 parameters in its structure. Typically 
only 25 to 30 percent of these parameters have a significant enough impact on the model 
prediction to be considered. Significant parameters in this model include parameters such as 
blood/air and tissue/blood partition coefficients, organ volumes, body weight, ventilation rates, 
and in vivo metabolic rates. 

Table 2-5 below provides the modeled exposure estimates corresponding to a range of 
blood levels. 

As shown in Table 2-6 below, the modeled mean perchloroethylene concentrations fall 
within the range of measured values for both air and water. 

Further interpretations of this analysis are discussed below: 

• The monitoring data are much older than the blood data (collection dates: air 
1975-1981, water 1973-1994 and blood 1988 - 1994). Thus, the exposure 
estimates derived from blood should better reflect current conditions. 

• Environmental monitoring data (especially for air) may not be very representative 
of actual exposures. For example, ambient air monitors are fixed units typically 
located on top of buildings and do not sample the air that a person actually 


37 













Table 2-5. Modeled Exposure Estimates for Tetrachloroethylene 


Blood Level 

Air Concentration 
(pg/m 3 ) 

Ingested Dose 
(pg/kg-day) 

Water Concentration 
(M-g/1) 

10th percentile (0.015 pg/I) 

1.34 

0.24 

8.4 

90th percentile (0.35 pg/1) 

31.2 

5.5 

192.5 

Mean (0.19 pg/1) 

17.0 

3 

105 


Table 2-6. Comparison of Measured and Modeled Perchloroethylene Concentrations 



Measured Range 

Modeled Mean 

Air 

0.2 to 30 pg/m 3 

18.5 pg/m 3 

Water 

0.0001 to 210 pg/1 

105 pg/1 


breathes throughout a day. Also, indoor air (which is not measured by ambient air 
monitors) may be a more important contributor to perchloroethylene exposure 
than outdoor air. In contrast, blood measurements reflect the actual exposure that 
an individual experiences. Thus, the exposure estimates derived from blood 
should more accurately reflect total exposure. 

Exposure estimates derived from blood cannot distinguish between exposure 
routes and sources. It is generally believed that perchloroethylene exposure 
occurs primarily via water consumption and air inhalation, but it is impossible to 
use the blood data to estimate how much of the total exposure is attributable to 
each. A wide range of combinations of exposures from air and water could have 
produced the measured blood levels. 


2.3.3.3 Environmental Fate and Transport 
2.3.3.3.1 Summary 

The summary is based on the data presented in the subsequent fate and transport 
subsections. 

Fate in Terrestrial Environments: The dominant fate of tetrachloroethylene released to 
surface soils is volatilization. Because of its low to moderate mobility in soils, 
tetrachloroethylene introduced into soil (e.g., landfills) has the potential to migrate through the 
soil into groundwater. Biodegradation under anaerobic conditions in soil and groundwater may 
occur at a relatively slow rate (half-lives on the order of months or longer (HSDB, 1996). 


38 

















Fate in the Atmosphere: In the atmosphere, tetrachloroethylene is expected to be present 
primarily in the vapor phase rather than sorbed to particulates because of its high vapor pressure. 
Removal by scavenging during wet precipitation is expected because of the moderate solubility 
of tetrachloroethylene in water (150 mg/L). The major degradation process affecting vapor phase 
tetrachloroethylene is photo-oxidation by hydroxyl radicals and the chlorine radicals formed by 
the hydroxyl radical reaction (half-life on the order of weeks to months). 

Fate in Aquatic Environments: The dominant fate of tetrachloroethylene released into 
surface waters is volatilization (predicted half-life of hours to days (HSDB, 1996)). 
Bioconcentration and sorption to sediments and suspended solids are not expected to be 
significant transport/partitioning processes. Although biodegradation is not expected to be a 
significant degradation process, any tetrachloroethylene that reaches the sediment will undergo 
slow anaerobic biodegradation. 

2.3.3.3.2 Transport and Partitioning 

Soil Adsorption/Mobility: A K oc of 1,685 is predicted for tetrachloroethylene based on 
its measured log octanol/water partition coefficient of 3.40. Actual K oc s calculated from studies 
with various soils and sediments are less than 250 (HSDB, 1996). Based on the reported and 
measured K oc s, tetrachloroethylene is expected to exhibit low to medium mobility in soil. 
Therefore, tetrachloroethylene may leach slowly to the groundwater particularly in soils with low 
organic content (HSDB, 1996). 

Volatilization: The dominant removal mechanism for tetrachloroethylene in surface 
waters is volatilization. The half-life will depend on wind and mixing conditions and is 
estimated to range from 3 hours to 14 days in rivers, lakes, and ponds based on laboratory and 
mesocosm experiments. Because of its high vapor pressure and relatively low soil adsorption 
coefficient, tetrachloroethylene is expected to volatilize from soil surfaces and also from 
suspended particulate matter in the atmosphere (HSDB, 1996). 

Bioconcentration: A bioconcentration factor of 226 is predicted for tetrachloroethylene 
based on its measured log octanol/water partition coefficient of 3.40. Actual BCFs measured in 
fish studies are less than 50. Therefore, bioconcentration in aquatic organisms should not be 
significant and there is little potential for biomagnification in the food chain (HSDB, 1996). 

2.3.3.33 Transformation and Degradation Processes 

Biodegradation: Under aerobic conditions, tetrachloroethylene undergoes 
biodegradation at a very slow rate with a half-life estimated at 6 months to a year. Little or no 
degradation has been observed in several aerobic tests with acclimated or unacclimated inocula 
nor in river die-away and mesocosm tests. Slow degradation under anaerobic conditions (half- 
lives of weeks to months) has been demonstrated in laboratory screening tests. 

Trichloroethylene is the major intermediate observed with traces of vinyl chloride and 
dichloroethylene isomers also formed (HSDB, 1996; Howard et al., 1991). 


39 




Photodegradation: Photolysis in the atmosphere or in aquatic environments is expected 
to proceed very slowly if at all. Tetrachloroethylene does not absorb UV light at wavelengths 
greater than 260 nm and thus will not directly photolyze. Based on measured rate data for the 
vapor phase photo-oxidation reaction with hydroxyl radicals and with the chlorine radicals 
formed during this reaction, the estimated half-life of tetrachloroethylene in the atmosphere is on 
the order of weeks to months, although one study has reported complete degradation in one hour. 
The main reaction products are phosgene, carbon tetrachloride, dichloroacetyl chloride, and 
trichloroacetyl chloride (HSDB, 1996; Howard et al., 1991). 

Hydrolysis: Tetrachloroethylene has no hydrolyzable groups. The rate constants at pH 3, 
7, and 11 have been measured to be zero in one study. Another study reported a half-life of 9 
months in purified, deionized water (HSDB, 1996; Howard et al., 1991) 

2.4 HUMAN EXPOSURE AND POPULATION ESTIMATES 

2.4.1 General U.S. Population 

The most important routes of exposure to PCE for the general population are inhalation 
of PCE in ambient air and ingestion of contaminated drinking water from contaminated aquifers 
and drinking water distributed in pipelines with vinyl liners (HSDB, 1996). Available data 
indicates that dermal exposure to PCE is not an important route of exposure for most people 
(ATSDR, 1997b). Exposure from inhalation of ambient air varies according to location. In rural 
and remote areas, background levels are generally in the low ppt range, and both low ppb and 
high ppt are found in urban and industrial areas, and areas near point sources of emissions 
(ATSDR, 1997b). 

Results of several studies have indicated that indoor air is a more significant source of 
exposure to PCE than outdoor air; reported concentrations in the air of four homes in North 
Carolina were consistently higher than the outdoor concentrations (ATSDR, 1997b). The 
detection of PCE in breast milk (see Section 2.3.3.2) indicates that infants may be exposed to 
PCE through breast feeding (ATSDR, 1997b). For the general population, the estimated amount 
of PCE that a person might breathe per day ranges from 0.08-0.2 mg/day and the most PCE 
people might drink in water is 0.0001-0.002 mg/day (ATSDR, 1997b). 

The EPA estimated that in 1985, 11,430,000 individuals (5.3 percent of the U.S. 
population using municipal water supplies) in the U.S. were exposed to PCE at concentrations 
>0.5 pg/1. Assuming a 70 kg person drinks 2 L/day of water containing 0.5 ppb PCE, the daily 
intake of PCE was 1 pg or 0.014 pg/kg/day (ATSDR, 1997b). Additionally, 874,000 individuals 
were estimated to be exposed to levels >5 pg/1 (IARC, 1995). General population exposure from 
ingestion of contaminated foods has been approximated by EPA assuming individual average 
daily intakes of 0.753 kg dairy products; 0.262 kg meat, fish, and poultry; 0.073 kg fats and oils; 
and 0.128 kg beverages (ATSDR, 1997b). The average daily intake of PCE was determined to 
be between 0-4 pg from dairy products; 0-1 pg from meat, fish, and poultry; 0-9.5 pg from fats 
and oils; and 0-0.06 pg from beverages (ATSDR, 1997b). 


40 




Showering or bathing with contaminated water is also a mechanism for PCE exposure. 
Using results from a study and a model, it was estimated that the shower air would contain an 
average of 1 ppm and the air above a bath tub would contain an average of 0.725 ppm if the 
water contained 1 mg/L of PCE (ATSDR, 1997b). The model assumed that the shower or bath 
used 100 liters of water, the air volume in the shower stall or above the bath tub was 3 m 3 , and 
the shower flow rate was 6.667 L/minute (ATSDR, 1997b). 

2.4.2 Occupational Exposure 

Persons with the greatest chance of elevated exposure are those engaged in occupational 
activities using PCE. In a survey conducted between 1981 and 1983 by NIOSH, it was estimated 
that approximately 688,110 employees in 49,025 plants in the U.S. were potentially exposed to 
PCE (ATSDR, 1997b). Further, in 1994 an independent industry estimate indicated that 
approximately 450,000 workers in dry cleaning operations in the U.S. may be exposed (IARC, 
1995). A NIOSH survey in 44 dry cleaning facilities showed PCE TWA exposures to machine 
operators ranged from 4.0 to 149 ppm with a geometric mean of 22 ppm. Mean exposures to 
pressers, seamstresses, and front counter workers were 3.3, 3.0, and 3.1 ppm, respectively 
(ATSDR, 1997b). 

Tetrachloroethylene has been identified in at least 771 of 1,430 hazardous waste sites that 
have been proposed for inclusion in the EPA National Priorities List (NPL) (ATSDR, 1997b). 
The number of sites evaluated is not known; the frequency of the sites are shown in Figure 2-2. 

2.4.3 Consumer Exposure 

In a study to determine potential sources of indoor air pollution, approximately 63 of 
1,159 common household products were found to contain PCE (IARC, 1995). Products that 
may contain PCE include adhesives; water repellents; fabric finishers; stain, spot, and rust 
removers; and wood cleaners (ATSDR, 1997b). Other consumer products that have been found 
to contain PCE are inks, polishes, rug and upholstery cleaners, sealants, and silicones. 

2.5 CHAPTER SUMMARY 

Table 2-7 summarizes the findings of TCE. 


41 





-> 

r 




_ 

- 


_ 

Z 



: - -i -T 


FREQUENCY 11 H 1- H 1 TO IS SITES 

56 TO 64 SITES 


16 TO 30 SITES 
7B SITES 


Figure 2-2. 
1997b) 


Frequency of NPL Sites with Tetrachloroethylene Contamination (Source: ATSDR, 


42 















































































































































































































































































































































































































































































Table 2-7. Tetrachloroethylene (Perchloroethylene) Summary 



Estimates 

Support 

Uses 

Dry cleaning and metal degreasing 

Well documented in numerous studies, 
recent information 

Production 

1.2 x 10 8 kg/yr 

1993 data 

Releases 

Air: 5.2 million lb/yr 

Water: 3,900 lb/yr 

Land: 4,300 lb/yr 

TRI (U.S. EPA, 1996) is primary source, so 
current but uncertain due to self reporting 
and exemptions 

Properties/Fate 

Volatile, water soluble, photo-oxidizes 
slowly in air, no significant biodegradation 
or bioconcentration 

Well documented in numerous studies, 
recent information 

Media Levels 

- Urban air: low ppb 

- Rural air: low ppt 

- Drinking water: 0.5-5 ug/L 

- Food: 0.3-3 ug/kg 

- Human blood: 0.19 ug/L 

- Human milk: 6.2 ug/L 

- Air data represents only 4 rural and 9 
urban locations, dates unclear 

- Blood data from NHANES III (n=590) 

- n’s and dates unclear for water, food, and 
human milk data 

General Population 

Exposure 

- Inhalation: 0.08-0.2 mg/d (urban) 

- Water ingestion: 0.1-2 ug/d 

- Dairy: 0-4 ug/d 

- Meat: 0-1 ug/d 

- Fats/oils: 0-9 ug/d 

- All estimates based on limited or unclear 
monitoring data (see above) 

Special Population 

Exposures 

- Nursing infants: ~4 ug/d 

- Workers in production plants, degreasing 
operations, dry cleaners (3-150) ppm 

- Representativeness of human milk data 
unknown 

- Worker data based on several recent 
surveys 


43 












I 


3.0 1,1,1-TRICHLOROETHANE (METHYL CHLOROFORM) 

3.1 CHEMICAL AND PHYSICAL PROPERTIES 

The information/data presented in this section and the supporting references were 
obtained from a retrieval from the Hazardous Substances Data Bank (HSDB, 1996). 

3.1.1 Nomenclature 


CAS No.: 

71-55-6 

Synonyms: 

Chloroethene; chloroform; methyl-, chlorotene; ethane, 
1,1,1-trichloro-; methyl chloroform; trichloroethane 

Trade Names: 

alpha-t; algylen; baltana; gemalgene; inhibisol; solvent 111 


3.1.2 Formula and Molecular Weight 

Molecular Formula: C 2 H 3 C1 3 

Molecular Weight: 133.43 

3.1.3 Chemical and Physical Properties 


Description: 

Colorless liquid (Patty, 1981-82); chloroform-like odor, sweetish 
(Hazard Chem. Data Vol. II, 1984-85). 

Boiling Point: 

74.0°C @ 760 mm Hg (CRC Handbook Chem. & Physics, 1994- 
95). 

Melting Point: 

-30.4°C (CRC Handbook Chem. & Physics, 1994-95). 

Density: 

1.3376 @ 20°C/4°C (Merck Index, 11th Ed., 1989). 

Spectroscopy Data: 

Index of refraction: 1.43838 @ 20°C/D (Merck Index, 10th Ed., 
1983); IR: 19461, NMR: 9171; Mass; 618 (Sadtler Research 
Laboratories Prism Collection) (Weast, 1985). 

Solubility: 

Soluble in acetone, benzene, methanol, carbon tetrachloride 
(Merck Index, 11th Ed., 1989); 4,400 mg/1 in water @ 20°C 
(Verschueren, 1983). 

Volatility: 

Vapor Pressure: 16.5 kPa @ 25°C (CRC Handbook, 1994-95) 

Vapor Density: 4.63, relative (air = 1) (Verschueren, 1983). 

Stability: 

No data. 


44 


I 



Reactivity: Although apparently stable on contact, mixtures with potassium 

(or its alloys) with a wide range of halocarbons (including 1,1,2- 
trichloroethane) are shock-sensitive and may explode with great 
violence on light impact. Violent decomposition with evolution 
of hydrogen chloride may occur when it comes into contact with 
aluminum or its alloys with magnesium (Handbook Reactive 
Chem. Hazards, 1985). Reacts with strong caustics; strong 
oxidizers; chemically-active metals such as zinc, magnesium 
powders; sodium and potassium; water (note: reacts slowly with 
water to form hydrochloric acid) (NIOSH Pocket Guide Chem. 
Haz, 1994). 


Octanol/Water 

Partition Coefficient: log Kow = 2.49 (Hansch. Log P Database, 1984) 

3.1.4 Technical Products and Impurities 

1,1,1-Trichloroethane is available commercially in the USA in technical and solvent 
grades, which differ only in the amount of stabilizer added to prevent corrosion of metal parts 
(IARC Monographs, V20:516, 1979). It is available as chlorothene SM (industrial grade) and 
aerothene TT (aerosol grade) (Kuney. Chemcyclopedia, 1988). 

Impurities include 1,2-dichloroethane, 1,1-dichloroethane, chloroform, carbon 
tetrachloride, trichloroethylene, 1,1,2-trichloroethane, and vinylidene chloride (Stewart, RD, et 
al., 1969). 

Stabilized grades contain 3-8% stabilizers such as nitromethane, N-methylpyrrole, 
butylene oxide, 1,3-dioxolane, and secondary butyl alcohols (IARC Monographs, V20:516, 

1979). Stabilizing agents which may be present in small amounts include: glycol diesters, 
ketones, nitriles, dialkyl sulfoxides, dialkyl sulfides, dialkyl sulfites, tetraethyl lead, nitroaliphatic 
hydrocarbons, 2-methyl-3-butyn-2-ol, tert-butyl alcohol, 1,4-dioxane, dioxolane, sec-butyl 
alcohol, and monohydric acetylenic alcohols (NIOSH, 1976). 

3.2 PRODUCTION AND USE 

The information/data presented in this section and the supporting references were 
obtained from a retrieval from the Hazardous Substances Data Bank (HSDB, 1996) and from 
ATSDR (1995). 

3.2.1 Production 

- (1990) 3.64 x 10" g (ATSDR, 1995); (1992) 3.13 x 10"g (HSDB, 1996). 

- Import Volume: (1991) 4.54 x 10 7 g; (1992) 5.99 x 10 9 g; (1993) 9.08 x 10 7 g 
(ATSDR, 1995). 


45 


- Export Volume: (1990) 5.2 x 10 10 g; (1991) 7.37 x 10'° g; (1992) 6.34 x 10 10 g; (1993) 
3.44 x 10'° g (ATSDR, 1995). 


3.2.2 Uses 

1,1,1-Trichloroethane is used as a solvent for adhesives (including food packaging 
adhesives) in pesticides, metal degreasing, textile processing, aerosols, lubricants, cutting oil 
formulations, cutting fluids, shoe polishes, spot cleaners, stain repellents, drain cleaners, and 
printing inks (ATSDR, 1995; HSDB, 1994). Its primary use in industry is for cold, dip, and 
bucket cleaning and in vapor degreasing operations of electric and electronic instruments, fabrics, 
wigs, and photographic film (ATSDR, 1995). It is also used as a chemical intermediate and for 
on-site cleaning of printing presses, food packaging machinery, and molds (ATSDR, 1995; 
HSDB, 1996). 1,1,1-Trichloroethane is also used extensively in household products that contain 
solvents. 

3.2.3 Disposal 

Generators of waste containing this contaminant (i.e., EPA hazardous waste numbers 
U226 and F002) must conform with USEPA regulations in storage, transportation, treatment, and 
disposal of waste [40 CFR 240-280, 300-306, 702-799]. 1,1,1-trichloroethane is a waste 
chemical stream constituent which may be subjected to ultimate disposal by controlled 
incineration, preferably after mixing with another combustible fuel. Complete combustion to 
prevent the formation of phosgene must be exercised (U.S. EPA, 1981 Engineering Handbook 
for Hazardous Waste Incineration). 1,1,1-Trichloroethane is a potential candidate for liquid 
injection incineration at a temperature range of 650 to 1,600°C and a residence time of 0.1 to 2 
seconds; for rotary kiln incineration at a temperature range of 820 to 1,600°C and residence times 
of seconds for liquids and gases, and hours for solids; and for fluidized bed incineration at a 
temperature range of 450 to 980°C and residence times of seconds for liquids and gases, and 
longer for solids (HSDB, 1996). Chemical treatability study results indicates that the chemical 
may be extractable with solvents, air and stream strippable, and treatable using biological 
treatment (U.S. EPA, 1982, Management of Hazardous Waste). Other methods that have shown 
promise for destruction of 1,1,1-trichloroethane are a combination of ozonation and ultraviolet 
treatment for groundwater and homogeneous sonochemical treatment for aqueous waste 
(ATSDR, 1995). 

3.3 POTENTIAL FOR HUMAN EXPOSURE 

3.3.1 Natural Occurrence 

1,1,1-Trichloroethane is not known to occur as a natural product. 

3.3.2 Occupational 

Humans may be exposed to 1,1,1-trichloroethane dermally and by inhalation of 
contaminated air at the workplace (HSDB, 1996). 


46 



3.3.3 Environmental 


1,1,1-Trichloroethane is likely to enter the environment from air emissions or in the 
wastewater from its production or use in vapor degreasing, metal cleaning, and other operations. 
It can also enter the environment in leachates and volatile emissions from landfills (HSDB, 
1996). Process and fugitive emissions may result from the use of both consumer and industrial 
products (ATSDR, 1995). Because 1,1,1-trichloroethane is used as a solvent in many products 
and is very volatile, it is most frequently found in the atmosphere due to volatilization from 
production and use (ATSDR, 1995). 

3.3.3.1 Environmental Releases 

Air: Trichloroethane has been found in the ambient air around chemical manufacturing 
areas, in remote and rural areas, and around suburban sites. Toxic Release Inventory (TRI) data 
are shown in Table 3-1. 

The TRI data for 1,1,1-trichloroethane have been correlated with industrial source code 
(SIC Codes) and shows that emissions of this chemical are associated with 122 different 
industrial classifications (ATSDR, 1995). The TRI data shown in Table 3-1 indicate that 1,1,1- 
trichloroethane emissions to air ranged from 166.3 million pounds in 1987 down to 38.1 million 
pounds in 1994 (TRI, 1996). 


Table 3-1. Releases of l,l>l"TrichIoroethane (lbs) 


Year 

Number of 
Reporting 
Facilities 

Fugitive Air 
Releases 

Stack Air 
Releases 

Surface 

Water 

Release 

Underground 

Injection 

Land 

Disposal 

POTW 

Transfer 

Other 

Transfers 

Total 

1987 

3494 

90,428,647 

75,825,060 

37,181 

28,325 

199,191 

412,010 

32,141,143 

199, 071,557 

1988 

3915 

92,995,587 

87,654,575 

95,624 

1,000 

204,923 

305,358 

19,389,542 

200,646,609 

1989 

4201 

94,100,022 

86,086,417 

27,564 

2,318 

70,547 

312,515 

16,815,840 

197,415,223 

1990 

4210 

85,672,408 

83,0994,85 

16,984 

1,586 

62,446 

173,444 

13.099,706 

182,126,059 

1991 

3732 

72,670,441 

71,770,764 

22,308 

2,805 

174,730 

253,812 

39,451,571 

184,346,431 

1992 

3210 

57,760,109 

59,857,572 

13,707 

561 

76,131 

119,263 

32,080,182 

149,907,525 

1993 

2111 

33,199,831 

31,568,263 

11,146 

2528 

42,743 

60,463 

20,842,953 

85,727,927 

1994 

1207 

20,070,741 

17,981,336 

1,980 

102 

2,732 

6,439 

11,387,618 

49,450,948 


Source: TRI, 1996. 


47 




















Other sources for small emissions of 1,1,1-trichloroethane to the atmosphere include coal 
fired plants, incineration of medical waste, incineration of industrial waste containing waste 
solvents and certain plastics, and municipal wastewater sludge (ATSDR, 1995). When contained 
in consumer products, 1,1,1-trichloroethane can be released to the atmosphere during application, 
drying, or curing of the consumer products. 

Water: 1,1,1-Trichloroethane has been reported in groundwater, surface water, and 
drinking water in the United States. It has also been reported in seawater. TRI data on water 
releases are presented in Table 3-1. 

Other Media: Levels of 1,1,1-trichloroethane has been reported in raw, processed, and 
prepared foods. Additionally, it has been detected in soils and sediments (ATSDR, 1995). TRI 
estimates of releases to land are presented in Table 3-1. 

3.33.2 Monitored Environmental Media Levels 

Air: Numerous studies have reported levels of 1,1,1-trichloroethane in air throughout the 
U.S. Monitoring data have been reported with sampling dates ranging primarily from years 1972 
through 1986. However, there are several studies for years 1987 through 1990. Measured 
concentrations in urban air range from 0.1 to 1 ppb; for large urban areas or areas near hazardous 
waste sites, levels <1,000 ppb have been observed (ATSDR, 1995; HSDB, 1996). Level of this 
chemical in rural areas typically are <0.2 ppb. ATSDR (1995c) provides a summary of 
monitored levels in ambient air in the U.S. that includes sampling dates, number of samples, 
concentrations (range and mean), study location, and author. Level of 1,1,1-trichloroethane in 
indoor air seems to depend on parameters such as outdoor concentration, age of building, 
individual practices, and building air exchange characteristics (ATSDR, 1995). 

Water: 1,1,1-Trichloroethane has been detected in surface water, groundwater, drinking 
water, rain, snow, effluent, and urban runoff (ATSDR, 1995). The levels detected in surface 
water and groundwater depends upon the sampling point location. For groundwater random 
samples, levels have ranged from 0 to 18 ppb; groundwater samples obtained near sources of 
release to soil have been as high as 11,000 ppb (ATSDR, 1995). Drinking water from reported 
surface or groundwater sources contained concentrations of 0.01 to 3.5 ppb (ATSDR, 1995). 

Levels in raw surface water in 105 U.S. cities were 0.2 ppb (median) and 1.2 ppb 
(maximum) (HSDB, 1996). In studies of surface water near industrialized sites, the measured 
levels ranged up to 334 ppb (HSDB, 1996). 

Other Media: 1,1,1-Trichloroethane has been detected in human adipose tissues (not 
detected - 830 ppb); milk; blood; and breath. It has been found in foods which include 
unprepared, uncooked foods; fruits; nuts; dairy products; etc. A range of the mean values for 
levels of 1,1,1-trichloroethane reported in ATSDR (1995) are shown in Table 3-2 for some of 
these foods. 1,1,1-Trichloroethane has been found in average concentrations in fish at 2.7 ppm; 
shrimp at <0.3 ppm; and clams and oysters ranging from 39 to 310 ppm. 


48 



Table 3-2. Level of 1,1,1-Trichloroethane in Food 


Food Type 

Concentration (ppb) (Range of Means) 

Cereals 

3-35 

Vegetables (processed/cooked) 

1-9 

Baked goods (breads, cookies, cakes) 

2-40 

Dairy products 

1-520 

Nuts/nut products 

10-228 

Meats, meat dishes (cooked/processed) 

2-76 

Fruits (raw/dried) 

2-32 

Infant/toddler blend 

6 


Source: ATSDR, 1995. 


The National Health and Nutrition Examination Survey (NHANES III) (1988-91) is a 
national survey of the U.S. civilian non-institutionalized population. It provides data to monitor 
changes in dietary, nutritional, and health status of the U.S. population. As part of this survey, 
data were analyzed for the level of selected VOCs in the blood. Figure 3-1 presents the level of 
1,1,1-trichloroethane in blood at selected percentiles. 

Levels of 1,1,1-trichloroethane in soils have been measured in grab samples from two 
former sludge lagoons of a solvent recovery operation, at a residence near a landfill, at a 
production facility, and at several NPL sites. The reported levels were 23,000 to 120,000 ppb at 
the lagoon, up to 230,000 ppb at the NPL sites, and 0.06 to 1.0 ppb at the production facility 
(ATSDR, 1995). Levels of 1,1,1-trichloroethane in sediment have been reported up to 2 ppb for 
non-NPL sites and ranged from 50 to 2,500 ppb at an NPL site (ATSDR, 1995). Monitoring data 
for the occurrence of 1,1,1-trichloroethane in soil is limited and may be due to its rapid 
volatilization from soil and/or its ability to leach through soil (ATSDR, 1995). 

3.3.3.3 Environmental Fate and Transport 

3.3.3.3.1 Summary 

The summary is based on the data presented in the subsequent fate and transport 
subsections. 

Fate in Terrestrial Environments: The dominant fate of 1,1,1-trichloroethane released 
to surface soils is volatilization. Because of its moderate mobility in soils, 1,1,1-trichloroethane 
introduced into soil (e.g., landfills) has the potential to migrate through the soil into groundwater. 

Fate in the Atmosphere: In the atmosphere, 1,1,1-trichloroethane is expected to be 
present primarily in the vapor phase rather than sorbed to particulates because of its moderate 
vapor pressure. Removal by scavenging during wet precipitation is expected because of the 
moderate solubility of 1,1,1-trichloroethane in water; 40 percent reductions in air concentrations 
have been reported on rainy days. The major degradation process affecting vapor phase 1,1,1- 
trichloroethane is photo-oxidation by hydroxyl radicals (half-life on the order of years). Due to 
its persistence, 1,1,1-trichloroethane will disperse over long distances and slowly diffuse into the 


49 






0.5 



10 20 30 40 50 60 70 80 90 


Population Percentile 


Source: NHANES III (Ashley, D., 1997, CDC). N=574 


Figure 3-1. Concentration of 1,1,1-Trichloromethane in Blood at Selected Population Percentiles 


50 












stratosphere where it would be rapidly degraded. The global atmospheric average half-life has 
been estimated to be 6 to 7 years (HSDB, 1996; ATSDR, 1995). 

Fate in Aquatic Environments: The dominant fate of 1,1,1-trichloroethane released to 
surface waters is volatilization (predicted half-life of hours to weeks depending on wind and 
mixing conditions). Bioconcentration and sorption to sediments and suspended solids are not 
expected to be significant transport/partitioning processes relative to volatilization. 

3.3.33.2 Transport and Partitioning 

Soil Adsorption/Mobility: The mean K oc range of 1,1,1-trichloroethane in a silty clay 
soil and sandy loam soil is 81 to 89. 1,1,1-Trichloroethane is sorbed strongly to peat moss but 
not at all to sand. From these measured K oc s and the fact that 1,1,1-trichloroethane is frequently 
detected in groundwater, it can be concluded that 1,1,1-trichloroethane is not sorbed strongly by 
soils. It can be expected to leach to groundwater particularly in soils with low organic content 
(HSDB, 1996). 

Volatilization: The dominant removal mechanism for 1,1,1-trichloroethane in surface 
waters is volatilization. The half-life will depend on wind and mixing conditions and is 
estimated to range from 3 to 29 hours in rivers, 4 to 12 days in lakes, and 5 to 11 days in ponds 
based on laboratory experiments. Because of its moderate vapor pressure and relatively low soil 
adsorption coefficient, 1,1,1-trichloroethane is expected to volatilize from soil and also from 
suspended particulate matter in the atmosphere. The cumulative evaporation loss of a mass of 
1,1,1-trichloroethane situated 1.0 to 1.3 meters beneath a soil surface for one year has been 
estimated to be 61.8 percent in sandy soil and 4.9 percent in clay soil (HSDB, 1996). 

Bioconcentration: A bioconcentration factor of 8.9 was measured in a 28-day test with 
bluegill sunfish. BCFs measured in fish studies are less than 10 for structurally similar 
halogenated aliphatic compounds. Therefore, bioconcentration in aquatic organisms should not 
be significant and there is little potential for biomagnification in the food chain (HSDB, 1996). 

3.3.3.33 Transformation and Degradation Processes 

Biodegradation: 1,1,1-Trichloroethane has been shown to undergo reductive 
dechlorination to 1,1 -dichloroethane and chloroethane under anaerobic conditions in laboratory 
tests using acclimated microorganisms with half-lives on the order of weeks to months. 
Biodegradation under aerobic conditions has also been demonstrated to occur at a slow rate 
(weeks to months) with vinylidene chloride formed as a degradation product (HSDB, 1996; 
Howard et al., 1991). 

Photodegradation: Direct photolysis is not important in the troposphere since 1,1,1- 
trichloroethane does not absorb light above 290 nm. In the stratosphere, photolysis is important 
and 1,1,1-trichloroethane will be rapidly degraded. Photolytic degradation has not been observed 
in aqueous media exposed to sunlight for one year. Based upon measured rate constants for the 
vapor phase photo-oxidation reaction with photochemically produced hydroxyl radicals, the half- 
life of 1,1,1-trichloroethane in the atmosphere is on the order of years. Products of 


51 



photodegradation include phosgene, chlorine radicals, and hydrochloric acid. Degradation is 
reported to be greatly increased by exposure to ozone and chlorine but no quantitative data are 
available (HSDB, 1996; Howard et ah, 1991). 

Hydrolysis: The hydrolysis half-life of 1,1,1-trichloroethane has been reported to range 
from 0.73 to 1.1 years. The half-life in water containing suspended sediment is 1.2 years. The 
product of hydrolysis is vinylidene chloride (HSDB, 1996; Howard et al., 1991). 

3.4 HUMAN EXPOSURE AND POPULATION ESTIMATES 

3.4.1 General U.S. Population 

The general population may be exposed to 1,1,1-trichloroethane through the inhalation of 
ambient air and inhalation of indoor air contaminated by use of household products containing 
this chemical. The general population may be potentially exposed to 1,1,1-trichloroethane 
through emissions from hazardous waste sites. 1,1,1 -Trichloroethane has been identified at 696 
of 1,408 NPL hazardous waste sites. The frequency of these sites in the U.S. is shown in Figure 
3-2. Inhalation is expected to be the predominant exposure route; however, exposure can also 
occur through ingestion of contaminated foods and drinking water and through dermal contact. 
Therefore, available data suggest that because of its ubiquitous occurrence in the environment 
and its use in many consumer products, much of the general population is exposed to low levels 
of 1,1,1 -trichloroethane (ATSDR, 1995). 

Exposure of the general population from the commercial use of products may potentially 
be more significant than exposure resulting from industrial release. ATSDR reported maximum 
exposure levels to this chemical during a variety of personal activities: visiting the dry cleaners 
(185 ppb); working in chemistry lab (18.5 ppb) and as lab technician (12 ppb); using pesticides 
(20 ppb); and using paint (20 ppb) (ATSDR, 1995). 

The average daily intake (ADI) for air is assumed in HSDB (1996) to be: in rural areas 
(0.110 ppb) - 12.2 jig; urban/suburban areas (0.420 ppb) - 46.5 pg; for residents in source 
dominated areas assume (1.2 ppb) - 133.0 pg. The ADI for water is assumed in HSDB (1996) to 
be: surface water source (0.4 ppb) - 0.8 pg; groundwater source (2.1 ppb) - 4.2 pg. ATSDR 
(1995) assumed an average urban air concentration of 1,1,1-trichloroethane of 1 ppb and the 
average rural concentration of 0.1 ppb and calculated daily nonoccupational intakes of 108 and 
10.8 pg/day, respectively. The estimate is based on an average human air intake of 20 m 3 /day. 
ATSDR (1995) noted that Wallace et al. (1985) has determined the mean daily air exposures for 
12 subjects at 2 urban areas at 37 mg and the mean daily intake from all sources (air, food, water) 
between 50 and 1,000 mg/day. 

3.4.2 Occupational Exposure 

NIOSH estimated in a 1981-1983 survey that approximately 2,528,300 workers were 
potentially exposed to 1,1,1-trichloroethane in the U.S. (ATSDR, 1995). Trichloroethane 
concentration in the air of various industries (degreasing, manufacture of electric components, 


52 




March 29, 200163 



FREQUENCY H H H H 1 TO IB SITES 

50 TO 58 SITES 


16 TO 28 SITES 
60 TO 71 SITES 


Figure 3-2. Frequency of NPL Sites with 1,1,1-Trichloromethane Contamination (Source: 
ATSDR, 1995) 


53 










































































































































































































































































































































































































































mixing and application of commercial resins, spray painting, and gluing) applications of 1,1,1- 
trichloroethane might result in elevated levels of exposure (ATSDR, 1995). Occupational 
exposures predominantly occur through inhalation pathways. 

3.4.3 Consumer Exposure 

In a shelf survey for household products containing methylene chloride, 14.1 percent of 
the samples and 47.8 percent of the product categories contained 1,1,1-trichloroethane (HSDB, 
1996). Consumer products that may contain this chemical include typewriter correction fluid, 
fingernail polish, paint thinner, caulking compounds, lacquer, paint removers, and antifreeze. A 
list of common household products that contain 1,1,1-trichloroethane is presented in Table 3-3. 


Table 3-3. 1,1,1-TrichIoroethane i n Common Household Products 


Product 

Concentration 
(% w/w) 

Product 

Concentration 
(% w/w) 

Adhesive cleaners 

0.1-95.0 

Oven cleaners 

97 

Adhesives 

0.2-121.1 

Paint removers/strippers 

0.1-25.7 

Aerosol spray paint 

0.2-1.0 

Primers 

1.2-61.8 

Battery terminal protectors 

37.1 

Rust removers 

0.7 

Belt lubricants 

11.4-72 

Silicone lubricants 

0.2-91.1 

Brake cleaners 

0.4-75.6 

Specialized aerosol cleaners 

0.2-83.8 

Carburetor cleaners 

0.2-0.3 

Spot removers 

10.5-110.8 

Circuit board cleaners 

NS 

Spray shoe polish 

11.4-62.3 

Door spray lubricants 

95.6 

Stereo/record player cleaners 

0.7 

Drain cleaner (nonacid) 

97.8 

Suede protectors 

4.8-118.5 

Electric shaver cleaners 

2.5-20.3 

Tape recorder cleaners 

0.2-101.5 

Engine degreasers 

0.2 

Tire cleaners 

0.1-90.3 

Fabric finishes 

77.9-85.1 

Transmission cleaner/lubricant 

113 

Gasket removers/adhesives 

0.2-1.0 

TV/computer screen cleaners 

0.3 

General purpose spray degreasers 

0.1-71.4 

Typewriter correction fluid 

6-110 

General purpose liquid cleaners 

72.7-126.7 

VCR cleaners 

97.8 

Ignition wire driers 

24.3-43.6 

Video disk cleaners 

0.6 

Lubricants 

0.1-104.5 

Water repellents 

0.2-116.2 

Miscellaneous nonautomotive 

12.5-67.5 

Wood cleaners 

12.3-20.4 

Miscellaneous automotive 

0.3-0.4 

Woodstain/vamishes/finishes 

0.1-21.4 


NS = not specified 
Source: ATSDR (1995) 

3.5 CHAPTER SUMMARY 

Table 3-4 summarizes the findings of 1,1,1-trichloroethane. 


54 







Table 3-4. 1,14-Trichloroethane (Methyl Chloroform) Summary 



Estimates 

Support 

Uses 

Metal cleaning and degreasing, many 
other solvent applications, chemical 
intermediate, many household 
products 

Well documented in recent 
studies 

Production 

3.13 x 10 s kg 

1992 data 

Releases 

49.45 x 10 6 lbs in 1994, mostly to air 

TRI (U.S. EPA, 1996) data is 
primary source, so data are 
current but uncertain due to self 
reporting and exemptions 

Properties/Fate 

Volatile, no significant bio¬ 
concentration, slow bio-degradation 

Well documented in recent 
studies 

Media Levels 

Air: outdoor urban - 0.545-5.45 

pg/m 3 

outdoor rural -<1.09 pg/m J 
Drinking Water: 0.01-3.5 ppb 
Groundwater: 0-18 ppb 

Some data on food and in many 
household items 

Data is dated and represent 
uncertain number of samples 

General Population 
Exposure 

Inhalation: rural - 12.2 pg/d 

urban/suburban - 46.5 
pg/d 

Water ingestion: surface water - 0.8 
pg/d; groundwater - 4.2 pg/d 

Values based on limited data 

Special Population 
Exposures 

Workers in dry cleaning, chemistry 
labs, lab tech, painting 

Data limited 


55 












4.0 1,2-DICHLOROETHYLENE 


4.1 CHEMICAL AND PHYSICAL PROPERTIES 

The information/data presented in this section and the supporting references were 
obtained from a retrieval from the Hazardous Substances Data Bank (HSDB, 1996). 

4.1.1 Nomenclature 

CAS No.: 540-59-0 


Synonyms: 

1,2-dichloroethene; acetylene dichloride; ethene, 1,2-dichloro 

Trade Names: 

Diform, NCI.C5603 


4.1.2 Formula and Molecular Weight 

Structural Formula: C 2 H 2 C1 2 
Molecular Weight: 96.95 

4.1.3 Chemical and Physical Properties 


Description: 

Colorless liquid (usually a mixture of cis and trans isomers); 


slightly acrid, chloroform-like odor (NIOSH Pocket Guide Chem. 
Haz., 1994). 

Boiling Point: 

55°C (Merck Index, 9th Ed., 1976). 

Melting Point: 

-50°C (Patty. Indus. Hyg. & Tox., 3rd Ed., 1981-82). 

Density: 

1.27 @ 25°C (liquid) (CHRIS Hazard Chem. Data Vol. II, 

1984-5). 


Spectroscopy Data: IR: 3645 (Sadtler Research Laboratories Prism Collection); Mass: 



203 (Atlas of Mass Spectral Data) (Weast. 1985. CRC Handbook 
Data Organic CPDS, Vol. I, II). 

Solubility: 

Soluble in alcohol, ether, acetone (cis- and trans-1,2- 
dichloroethylenes) (CRC Handbook Chem. & Physics, 1994-1995) 
Soluble in most organic solvents (Merck Index, 11th Ed., 1989) 

Volatility: 

Vapor Pressure: 324 torr at 25°C (Patty. Indus. Hyg. & Tox, 3rd. 
Ed., Vol. 2A, 2B, 2C, 1981-1982). 

Stability: 

Gradually decomposed by air, light, and moisture, forming HC1 
(Merck Index, 10th Ed., 1983). 


56 




Reactivity: The reaction of 1,2-dichloroethylene and potassium hydroxide 

produces chloroacetylene, which is explosive and spontaneously 
flammable in air. It is highly toxic. The addition of sodium, 
caustic, or caustic solution to 1,2-dichloroethylene may form 
monochloroacetylene which is spontaneously flammable in air 
(Fire Protect Guide Hazard Matls, 10th Ed., 1991). May release 
explosive chloroacetylene by the contact with copper or copper 
alloys (Tox & Hazard Indus Chem Safety Manual, 1988). 
Incompatible with alkalies, difluoromethylene dihypofluorite, and 
nitrogen tetraoxide (Sax, 1984). Reactive with strong oxidizers, 
strong alkalis, potassium hydroxide, copper (Note: usually contains 
inhibitors to prevent polymerization) (NIOSH Pocket Guide Chem 
Haz, 1994). 


Octanol/Water 

Partition Coefficient: No data 

4.1.4 Technical Products and Impurities 

1,2-Dichloroethylene is produced in the following grades: technical; As cis, trans; and as 
a mixture of both (Sax, 1987). Technical 1,2-dichloroethylene consists of 60%, 40% cis- trans¬ 
isomers (ACGIH, 1985). 

4.2 PRODUCTION AND USE 

The information/data presented in this section and the supporting references were 
obtained from a retrieval from the Hazardous Substances Data Bank (HSDB, 1996) and ATSDR 
(1996a). 

4.2.1 Production 

No information concerning U.S. production, import, or export volumes was identified. 

4.2.2 Uses 

1,2-Dichloroethylene has been used as a solvent for fats, phenol, camphor; for retarding 
fermentation (Merck Index, 11th Ed., 1989); solvent for natural rubber; coolant in refrigeration 
plants; low temperature solvent; and a special-purpose solvent (HSDB, 1996; ATSDR, 1996a). 

It has also been used in extraction of dyes, caffeine, fats from animal flesh; perfumes; lacquers; 
thermoplastics; and organic synthetics (Sax, 1987). Although cis- and trans-isomers of 1,2- 
dichloroethylene have had use as solvents and chemical intermediates, neither of the isomers has 
developed wide industrial usage in the U.S., partly because of their flammability (Patty. Indus 
Hyg & Tox, 3rd Ed., Vol. 2A, 2B, 2C, 1981-82). 1,2-dichloroethylene obtained as a byproduct is 
used as feed stock for the synthesis of tri- and perchloroethylene (Ullmann’s Encyc Indust Chem, 
5th Ed., Vol. Al, 1985-present). It also has miscellaneous uses such as a liquid dry cleaning 


57 


agent; cleaning agent for printed circuit boards; for food packaging adhesive; and germicidal 
fumigant. The extent of these continued uses has not been confirmed (ATSDR, 1996a). 

In applications where dichloroethylenes could be used as solvents and for low 
temperature extraction processes, they have been replaced with methylene chloride (Ullmann’s 
Ency Indus Chem, 5th Ed., 1985-present). 

4.2.3 Disposal 

1,2-Dichloroethylene is a potential candidate for rotary kiln incineration at a temperature 
range of 820 to 1,600°C and residence times of seconds for liquids and gases and hours for 
solids; for fluidized bed incineration at a temperature range of 450 to 980°C and residence times 
of seconds for liquids and gases, and longer for solids; and for liquid injection incineration at a 
temperature range of 650 to 1,600°C and a residence time of 0.1 to 2 seconds (trans-1,2- 
dichloroethylene) (USEPA. 1981. Engineering Handbook for Hazardous Waste Incineration). 
This compound should be susceptible to removal from wastewater by air stripping 
(USEPA/ORD. 1980. Innovative and Alternative Technology Assessment Manual). 

Incineration is a disposal method, preferably after mixing with another combustible fuel. Care 
must be exercised to assure complete combustion to prevent the formation of phosgene. An acid 
scrubber is necessary to remove the halo acids produced. The recommendable method is 
incineration (Un. Treat Disposal Methods Waste Chem Data Series No. 5, 1985). 

At the time of review, criteria for land treatment or burial (sanitary landfill) disposal 
practices are subject to significant revision. Prior to implementing land disposal of waste residue 
(including waste sludge) consult with environmental regulatory agencies for guidance on 
acceptable disposal practices (HSDB Scientific Review Panel; HSDB, 1996). 

4.3 POTENTIAL FOR HUMAN EXPOSURE 

4.3.1 Natural Occurrence 

No information on natural occurrence of 1,2-dichloroethylene was identified. 

4.3.2 Occupational 

Occupational potential for exposure is reported in Section 5 and Section 6 for the cis and 
trans isomers, respectively. 

4.3.3 Environmental 

Most of the 1,2-dichloroethylene released into the environment will eventually enter the 
groundwater or the atmosphere (ATSDR, 1996a). Releases to the environment are a result of 
process and fugitive emissions from production and use as a chemical intermediate; leaching 
from landfills; evaporation from wastewater streams, landfills, and solvents; emissions from 
heating or combustion PVC and vinyl copolymers; and formation via anaerobic biodegradation 
of some chlorinated solvents (ATSDR, 1996a). 


58 





4.3.3.1 Environmental Releases 


Air: Releases of 1,2-dichloroethylene to air are usually the result of emissions from 
industrial production and use facilities, contaminated waste disposal sites, and emissions from 
pyrolysis/combustion of certain plastic resins. TRI estimates for releases to the air in 1991 
totaled 44,782 pounds (>99 percent of total TRI estimated environmental releases) (ATSDR, 
1996a). 


Water: 1,2-dichloroethylene may be released to surface waters, groundwater, and has 
been detected in drinking water. It may be released to surface waters through runoff from 
contaminated waste disposal sites, wastewater from industrial sources, and from some POTWs. 
According to TRI estimates for 1993, a total of 28 pounds of 1,2-dichloroethylene (<0.1 percent 
of total releases to the environment) were released to water from reporting manufacturing and 
processing facilities (ATSDR, 1996a). 

1,2-dichloroethylene may be released to groundwater due to leaching from contaminated 
waste disposal sites and cracked sewer interceptors carrying industrial waste contaminated with 
this chemical. It may also be released to groundwater as a result of anaerobic degradation of 
highly chlorinated ethenes (TCE, PCE) and ethanes present in groundwater (ATSDR, 1996a). 

1,2-dichloroethylene’s presence in drinking water may be attributed to raw water source 
contamination; however, there is little documentation of direct groundwater contamination. 

Other Media: The cis and trans isomers of 1,2-dichloroethylene are released to soil from 
disposal of waste contaminated with this chemical. Additionally, they may also be found in 
landfills from anaerobic biodegradation of PCE, TCE, 1,1,1-trichloroethane, and 1,1,2,2- 
tetrachloroethane (ATSDR, 1996a). TRI estimates for 1993 indicated that no 1,2- 
dichloroethylene was released to land from manufacturing and processing facilities (ATSDR, 
1996a). Available data are not sufficient to estimate the amount of 1,2-dichloroethylene released 
to soil and to sediments. 

4.3.3.2 Monitored Environmental Media Levels 

Air: 1,2-dichloroethylene has been detected in ambient air samples in various urban 
locations throughout the U.S. It has also been detected in the gas from various landfills in the 
U.S. Levels found in the ambient air ranged from <0.1 to 2.6 ppb, and levels in the gas from 
landfills ranged from 70 ppb (mean) to 75,600 ppb (maximum values; trans isomer) (ATSDR, 
1996a). 1,2-dichloroethylene detected in the indoor air of 2 studies were 0.015 ppb and 8.1 ppb, 
respectively (ATSDR, 1996a). The data reported in most studies were not isomer-specific. In 
the EPA National Ambient Database update, outdoor ambient concentrations of 1,2- 
dichloroethylene averaged 0.326 ppb. A median value of 0.037 ppb was also reported. These 
reported levels were base on 161 data points (ATSDR, 1996a). According to ATSDR (1996a), 
the efficiency of waste treatment plants has improved and loadings to receiving waters have 
decreased. But, this decrease has often resulted in increased emissions to the atmosphere as the 
volatile constituents are removed through processes such as air stripping (ATSDR, 1996a). 


59 


Water: Concentrations of 1,2-dichloroethylene found in water reported in ATSDR 
(1996a) are described below. These ranges are based on various studies. 

• Surface water: not detected - 1,370.5 ppb (maximum value) 

• Groundwater: 0.25-0.28 ppb (average value) - 50,000 ppb (maximum value; trans 
isomer) 

• Drinking water: trace - 64 ppb (maximum value - groundwater source) 

• Leachate: 1.4-470 (cis isomer) ppb - 45-800 ppb (average concentration of 
leachate; maximum value) 

• Aqueous Lagoon: 50 ppb (trans isomer) 

• Wastewater at various industries: 1.6 ppb (cis isomer) - 2,265 ppb (trans isomer; 
median value) 

• Rainwater: 0.230 ppb (1 sample) 

A maximum concentration of 33 ppb for cis isomer was found in a shallow unconfirmed aquifer 
receiving waste water from metal plating operations. The EPA Contract Laboratory Program 
(CLP) data base has reported trans isomer mean concentrations ranging from 5 to 4,000 ppb at 8 
of 357 hazardous waste sites. 

Other Media: Trans 1,2-dichloroethylene concentrations ranging from 22 to 55 g/L have 
been detected in municipal sludge from various treatment throughout the United States (1996a), 
while 0.04 ppm (mean value) to 0.05 ppm (maximum value) of 1,2-dichloroethylene were found 
in fish tissues from Commencement Bay in Tacoma, Washington (1996a). Monitoring data for 
levels of 1,2-dichloroethylene in soil are very limited. The mean concentration range of 5 to 
4,000 ppb was reported at 87 of 357 hazardous waste sites (ATSDR, 1996a). However, the trans 
isomer was reported in all cases (ATSDR, 1996a). According to ATSDR (1996a), the available 
data for 1,2-dichloroethylene in soil are limited to data from hazardous waste site monitoring. 

4.3.3.3 Environmental Fate and Transport 

4.3.3.3.1 Summary 

The summary is based on the data presented in the subsequent fate and transport 
subsections. 

Fate in Terrestrial Environments: The dominant fate of 1,2-dichloroethylene released 
to surface soils is volatilization. Some 1,2-dichloroethylene may leach downward in the soil 
column because of the high water solubility and low K oc values of the two isomers. Also, 1,2- 
dichloroethylene is formed under anaerobic conditions in soil, groundwater, and sediments as a 
breakdown product from microbial reductive dehalogenation of the common industrial solvents 
trichloroethylene, tetrachloroethylene, and 1,1,2,2,-tetrachloroethane. The fate of 1,2- 
dichloroethylene in subsurface soils and groundwater is slow anaerobic degradation with the 
formation of vinyl chloride as a degradation product. 

Fate in the Atmosphere: In the atmosphere, 1,2-dichloroethylene is expected to be 
present in the vapor phase rather than sorbed to particulate matter. Removal by scavenging 


60 









during wet precipitation is expected because of the high solubility of the two isomers. The 
predominant degradation process affecting both isomers is photo-oxidation by hydroxyl radicals. 
Predicted half-lives for this reaction are 3.6 and 8 days for the trans- and cis- isomers, 
respectively. 

Fate in Aquatic Environments: The dominant fate of 1,2-dichloroethylene released to 
surface waters is volatilization (predicted half-life of 3 hours). Bioconcentration and sorption to 
sediments and suspended solids are not expected to be significant transport/partitioning 
processes. Although biodegradation is not expected to be a significant degradation process, any 
1,2-dichloroethylene that reaches the sediment will undergo slow anaerobic biodegradation. 

4.33.3.2 Transport and Partitioning 

Soil Adsorption/Mobility: The relatively low predicted soil adsorption coefficients (K oc ) 
for cis- and trans-1,2-dichloroethylene, 36 and 49, respectively, indicate that adsorption of the 
1,2-dichloroethylene isomers to soil, sediment, and suspended solids is not a significant fate 
process. As a consequence, these isomers should show high mobility in soil (HSDB, 1996; 
Howard, 1993). 

Volatilization: The dominant removal mechanism for the dichloroethylene isomers in 
surface waters is volatilization. The Henry's Law constants for cis- and trans- dichloroethylene 
are 0.00408 and 0.00938, respectively. Based on these values, the estimated half-lives for 
volatilization of cis- and trans-dichloroethylene from a model river 1 m deep with a 1 m/sec 
current and a 3 m/sec wind speed are 3.1 and 3.0 hours, respectively. Similarly, the volatilization 
half-lives from a 1 m deep body of water predicted from laboratory volatilization studies are 5.0 
and 6.2 hours, respectively. Because of their high vapor pressures, both isomers are also 
expected to readily volatilize from soil surfaces and also from suspended particulate matter in the 
atmosphere (HSDB, 1996; Howard, 1993). 

Bioconcentration: Bioconcentration factors of 15 and 22 are predicted for cis- and trans- 
dichloroethylene, respectively, based on their respective octanol/water partition coefficients. 
Therefore, bioconcentration in aquatic organisms should not be significant and there is little 
potential for biomagnification in the food chain (HSDB, 1996; Howard, 1993). 

4.3.3.33 Transformation and Degradation Processes 

Biodegradation: The results of most aerobic biodegradation studies indicate that 1,2- 
dichloroethylene is recalcitrant to aerobic degradation in soil and water (i.e., half-lives on the 
order of months); however, one study reported half-lives on the order of days to weeks. Several 
studies have demonstrated that both isomers will undergo slow anaerobic biodegradation in soils 
and sediments with half-lives on the order of months or longer. Vinyl chloride is a degradation 
product (HSDB, 1996; Howard, 1993; Howard et al„ 1991). 

Photodegradation: In the atmosphere, cis- and trans-1,2-dichloroethylene react with 
photochemically produced hydroxyl radicals resulting in half-lives of 8 and 3.6 days, 
respectively. The only product positively identified from this reaction is formyl chloride. Photo- 


61 




oxidation through reaction with ozone is much slower, on the order of months. Because cis- and 
trans-l,2-dichloroethylene absorb only a small amount of UV light in the environmentally 
significant range, direct photolysis is an insignificant fate process (HSDB, 1996; Howard, 1993; 
Howard et al., 1991). 

Hydrolysis: The two isomers of 1,2-dichloroethylene contain no hydrolyzable groups 
(Howard et al., 1991) 

4.4 HUMAN EXPOSURE AND POPULATION ESTIMATES 

4.4.1 General U.S. Population 

The general population may be exposed to low levels ranging from 0.013 to 0.076 ppb of 
1,2-dichloroethylene through inhalation of contaminated air in urban areas (ATSDR, 1996a). 
ATSDR (1996a) calculated the corresponding average daily intake of 1 to 6 pg/day based on an 
average air intake of 20 m 3 /day. HSDB (1996) has reported the following assumed 
concentrations for average daily intake: 

Air intake - assume air concentration of 68 ppt (5.4 fig) 

Water intake - assume water concentration from contaminated sources of 1.1 ppb 

(2.2 pg) when drinking water is contaminated 

The general population with potentially the highest exposures are those living near 
production/processing facilities, municipal wastewater treatment plant, hazardous waste sites, 
and municipal landfills. Potential exposure exists in air downwind of these sites and in the 
contaminated drinking water from groundwater down gradient from the sites (ATSDR, 1996a). 

Cis-l,2-dichloroethylene has been identified in 146 of the 1,430 current or former EPA 
National Priorities List (NPL) hazardous waste sites and trans -1,2-dichloroethylene has been 
identified in at least 563 of the current or former NPL sites (ATSDR, 1996a). Although the 
number of sites evaluated for this chemical is not known, the frequency of these sites has been 
determined and is presented in Figure 4-1. 

4.4.2 Occupational Exposure 

According to a 1981-1983 NIOSH survey, a statistical estimate of 215 workers in the 
U.S. are potentially exposed to 1,2-dichloroethylene (mixture of cis and trans isomers) in the 
workplace (ATSDR, 1996a). An estimated 61 workers are potentially exposed to the cis isomer 
(ATSDR, 1996a). An estimate for potential occupational exposure to the trans isomer was not 
estimated from the survey. 


62 





Figure 4-1. Frequency ofNPL Sites with 1,2-Dichloroethene (Unspecified) Contamination 
(Source: ATSDR, 1996a) 




i 

i 


63 


















































































































































4.4.3 


Consumer Exposure 


Readily available data were not found on consumer exposures for 1,2-dichloroethylene. 
4.5 CHAPTER SUMMARY 

Table 4-1 summarizes the findings of 1,2-dichloroethylene. 


Table 4-1. 1,2-Dichloroethylene Summary 



Estimates 

Support 

Uses 

Many solvent applications 

Well documented 

Production 

No recent information was identified 


Releases 

44.8 x 10 3 lbs/year to air (>99% of total 
environmental releases) 

TRI (U.S. EPA, 1996) data 

Properties/Fate 

Volatile; insoluble in water; relatively stable 
in air; flammable; significant 
bioconcentration not expected 

Well documented 

Media Levels 

Air: <0.545-14.16 pg/m 3 

Ambient air: 0.202 pg/m 3 

Surface water: ND-1,370 ppb 

Groundwater: 0.25-0.28 ppb (average value) 
Drinking water: trace-64 ppb 

ATSDR (1996a) 

161 data points, from EPA National 

Ambient Database 

General Population 

Exposure 

Inhalation: 1 to 6 ug/d 

ATSDR (1996a) 

Special Population 

Exposures 

215 workers are potentially exposed 

Data from early 1980s 


64 















5.0 CIS-1,2-DICHLOROETHYLENE 

5.1 CHEMICAL AND PHYSICAL PROPERTIES 

The information/data presented in this section and the supporting references were 
obtained from a retrieval from the Hazardous Substances Data Bank (HSDB, 1996). 

5.1.1 Nomenclature 


CAS No.: 

156-59-2 

Synonyms: 

1,2-cis-dichloroethene; cis-dichloroethylene; ethene, 1,2-dichloro-, 
ethylene; 1,2-dichloro- 

Trade Names: 

Acetalyne dichloride 


5.1.2 Formula and Molecular Weight 

Structural Formula: C 2 H 2 C1 2 
Molecular Weight: 96.95 

5.1.3 Chemical and Physical Properties 


Description: 

Liquid (Merck Index, 11th Ed., 1989); colorless (Tox & Hazard 


Indus Chem Safety manual, 1982); Sweetish (Ullmann’s Encyc 
Indust Chem, 5th Ed., Vol Al, 1985-present). 

Boiling Point: 

60.3°C @ 760 mm Hg (CRC Handbook Chem & Physics, 75th 
Ed., 1994-1995). 

Melting Point: 

-80.5°C (CRC Handbook Chem & Physics, 75th Ed., 1994-1995). 

Density: 

1.2837 @ 20°C/4°C (CRC Handbook Chem & Physics, 75th Ed., 
1994-1995). 


Spectroscopy Data: Index of refraction: 1.4490 20°C/D; maximum absorption (vapor): 

greater than 200 nm (CRC Handbook Chem & Physics, 75th Ed., 


Solubility: 

1994-1995). Sadder reference number: 3645 (IR, Prism) (Weast, 
1979). Refractive index: 1.4519 @ 15°C (Flick. Indust Solvents 
Handbook, 1985). Mass: 203 (Atlas of Mass Spectral Data) 
(Weast, 1985). 

Water solubility = 0.35 g/100 g @ 25°C (Kirk-Othmer, 4th Ed., 
Vol. 1, 1991-present). Soluble in alcohol, acetone, ether, benzene, 
and chloroform (Weast. Hdbk Chem & Phys, 67th Ed., 1986-87). 


65 


Volatility: Vapor Pressure: 273 mm Hg @ 30°C. 

Vapor Density: 3.54 g/1 (at bp, 760 mm Hg) (Flick. Indust Solvents 
Hdbk, 1985). 

Stability: Decomposes slowly on exposure to air, light, and moisture. 

Reactivity: May release explosive chloroacetylene by the contact with copper 

or copper alloys (1,2-dichloroethylene (ITII. Tox & Hazard Indus 
Chem Safety Manual, 1988). Reacts with strong oxidizers (1,2- 
dichloroethylene (Sittig. Handbook Toxic Hazard Chem & 
Carcinog, 2nd Ed., 1985). 

Octanol/Water 

Partition Coefficient: log Kow =1.86 (Hansch. Log P Database, 1987) 

5.1.4 Technical Products and Impurities 

No data were identified. 

5.2 PRODUCTION AND USE 

The information/data presented in this section and the supporting references were 
obtained from a retrieval from the Hazardous Substances Data Bank (HSDB, 1996). 

5.2.1 Production 

The U.S. production in 1977 was at least 5.0 x 10 8 g (captive production) (SRI). More 
recent production data were unavailable. No data were identified for import and export volumes. 

5.2.2 Uses 


Cis-1,2-dichloroethylene is used as a solvent (isomeric mixture) for perfumes, dyes, and 
lacquers; solvent (as mixture) for thermoplastics, fats, and phenols; solvent (as mixture) for 
camphor and natural rubber; chemical intermediate (as isomeric mixture) for chlorinated 
compound; and an agent in retarding fermentation (SRI). It is also used as a solvent in waxes, 
resins, and acetylcellulose and used in the extraction of rubber, as a refrigerant, in the 
manufacture of pharmaceuticals and artificial pearls and in the extraction of oils and fats from 
fish and meat (Sittig. Handbook Toxic Hazard Chem & Carcinog, 2nd Ed., 1985). 

Although cis- and trans-isomers of 1,2-dichloroethylene have had use as solvents and 
chemical intermediates, neither isomer has developed wide industrial usage in the U.S., partly 
because of their flammability (Patty. Indus Hyg & Tox, 3rd Ed., 1981-82). 1,2-dichloroethylenes 
obtained as byproducts are used as feed stock for the synthesis of tri- and perchloroethylene 
(Ullmann’s Encyc. Indust. Chem., 5th Ed., Vol la, 1985-present). 


66 


In applications where dichloroethylenes could be used as solvents and for low 
temperature extraction processes, they have been replaced by methylene chloride (Ullmann’ s 
Encyc Indust Chem, 5th Ed., Vol Al, 1985-present). 

5.2.3 Disposal 

1,2-dichloroethylene may be disposed of by atomizing in a suitable combustion chamber 
equipped with an appropriate effluent gas cleaning device (NIOSH/OSHA. Occupat Health 
Guide Chem Hazards, 1981). Incineration is a disposal method, preferably after mixing with 
another combustible fuel. Care must be exercised to assure complete combustion to prevent the 
formation of phosgene. An acid scrubber is necessary to remove the halo acids produced (Sittig. 
Handbook Toxic Hazard Chem & Carcinog, 2nd Ed, 1985). This compound should be 
susceptible to removal from wastewater by air stripping (USEPA/ORD. 1980. Innovative and 
Alternative Technology Assessment Manual). 

* 

At the time of review, criteria for land treatment or burial (sanitary landfill) disposal 
practices are subject to significant revision. Prior to implementing land disposal of waste residue 
(Including waste sludge) consult with environmental regulatory agencies for guidance on 
acceptable disposal practices (HSDB Scientific Review Panel; HSDB, 1996). 

5.3 POTENTIAL FOR HUMAN EXPOSURE 

5.3.1 Natural Occurrence 

Cis-l,2-dichloroethylene is not known to occur naturally. 

5.3.2 Occupational 

Occupational exposure to cis-l,2-dichloroethylene is expected to be through dermal 
contact with the vapor and liquids and through inhalation of contaminated air at the work place 
(HSDB, 1996). 

5.3.3 Environmental 

5.3.3.1 Environmental Releases 

Cis-1,2-dichloroethylene may be released to the environment in emissions and 
wastewater during its production and use as a solvent and extract (HSDB, 1996). The cis isomer 
is apparently more commonly found than the trans isomer, but is usually mistakenly listed as the 
trans isomer. The Michigan Department of Health has reported that it has the capability of 
distinguishing between the two isomers and where concentrations are high, they occasionally find 
traces of the trans isomer (HSDB, 1996). Under aerobic conditions that may exist in landfills or 
sediments, 1,2-dichloroethylenes may be present as breakdown products from reduction 
dehalogenation of trichloroethylene and tetrachloroethylene (HSDB, 1996). 


67 


5.33.2 Monitored Environmental Media Levels 


According to HSDB (1996), an assessment of the sources of the cis-l,2-dichloroethylene 
is complicated because the cis isomer was a priority pollutant, unlike the trans isomer. These 
isomers cannot be differentiated using the EPA standard method analysis. Therefore, monitoring 
reports have erroneously listed the trans isomer when the cis isomer is present (HSDB, 1996). 
(See Section 4.0 (1,2-Dichloroethylene) for more information on environmental levels.) 

Air: For urban/suburban areas in the U.S., reported levels for 669 sites/samples were 68 
ppt (median values) and 3,500 ppt (maximum value). Source areas (101 sites/samples) reported 
levels were 300 ppt (median) and 6,700 ppt (maximum value) (HSDB, 1996). 

Water: Cis-l,2-dichloroethylene was found in Miami drinking water at 16 ppb, 
Cincinnati and Philadelphia at 0.1 ppb, but was not found in 7 other drinking waters surveyed 
(HSDB, 1996). Raw water from a well in Wisconsin contained 83.3 ppb of this chemical. The 
Biscayne Aquifer (near the Miami inactive drum recycling hazardous waste site) that supplies 
drinking water to Dade County, Florida, contained 0-26 ppb. Shallow groundwater near the site 
had reported levels of 839 and 13.3-17.9 ppb (HSDB, 1996). 

Other Media: Data were not available for levels in food, plants, fish, animals, and milk. 

53.3.3 Environmental Fate and Transport 
5.333.1 Summary 

The summary is based on the data presented in the subsequent fate and transport 
subsections. 

Fate in Terrestrial Environments: The dominant fate of 1,2-dichloroethylene released 
to surface soils is volatilization. Some 1,2-dichloroethylene may leach downward in the soil 
column because of the high water solubility and low K^. values of the two isomers. Also, 1,2- 
dichloroethylene is formed under anaerobic conditions in soil, groundwater, and sediments as a 
breakdown product from microbial reductive dehalogenation of the common industrial solvents 
trichloroethylene, tetrachloroethylene, and 1,1,2,2,-tetrachloroethane. The fate of 1,2- 
dichloroethylene in subsurface soils and groundwater is slow anaerobic degradation with the 
formation of vinyl chloride as a degradation product. 

Fate in the Atmosphere: In the atmosphere, 1,2-dichloroethylene is expected to be 
present in the vapor phase rather than sorbed to particulate matter. Removal by scavenging 
during wet precipitation is expected because of the high solubility of the two isomers. The 
predominant degradation process affecting both isomers is photo-oxidation by hydroxyl radicals. 
Predicted half-lives for this reaction is 8 days for the cis- isomers. 

Fate in Aquatic Environments: The dominant fate of 1,2-dichloroethylene released to 
surface waters is volatilization (predicted half-life of 3 hours). Bioconcentration and sorption to 
sediments and suspended solids are not expected to be significant transport/partitioning 


68 




processes. Although bio-degradation is not expected to be a significant degradation process, any 
1,2-dichloroethylene that reaches the sediment will undergo slow anaerobic biodegradation. 

53.3.3.2 Transport and Partitioning 

Soil Adsorption/Mobility: The relatively low predicted soil adsorption coefficients (K oc ) 
for cis-l,2-dichloroethylene of 36 indicate that adsorption of the cis-l,2-dichloroethylene isomer 
to soil, sediment, and suspended solids is not a significant fate process. As a consequence, these 
isomers should show high mobility in soil (HSDB, 1996; Howard, 1993). 

Volatilization: The dominant removal mechanism for the dichloroethylene isomers in 
surface waters is volatilization. The Henry's Law constants for cis-dichloroethylene is 0.00408. 
Based on this value, the estimated half-life for volatilization of cis-dichloroethylene from a 
model river 1 m deep with a 1 m/sec current and a 3 m/sec wind speed is 3.1 hours. Similarly, 
the volatilization half-life from a 1 m deep body of water predicted from laboratory volatilization 
studies is 5.0 hours. Because of its high vapor pressures, this isomer is also expected to readily 
volatilize from soil surfaces and also from suspended particulate matter in the atmosphere 
(HSDB, 1996; Howard, 1993). 

Bioconcentration: Bioconcentration factors of 15 is predicted for cis-dichloroethylene, 
based on its respective octanol/water partition coefficient. Therefore, bioconcentration in aquatic 
organisms should not be significant and there is little potential for biomagnification in the food 
chain (HSDB, 1996; Howard, 1993). 

5.3.3.33 Transformation and Degradation Processes 

Biodegradation: The results of most aerobic biodegradation studies indicate that 1,2- 
dichloroethylene is recalcitrant to aerobic degradation in soil and water (i.e., half-lives on the 
order of months); however, one study reported half-lives on the order of days to weeks. Several 
studies have demonstrated that both isomers will undergo slow anaerobic biodegradation in soils 
and sediments with half-lives on the order of months or longer. Vinyl chloride is a degradation 
product (HSDB, 1996; Howard, 1993; Howard et al., 1991). 

Photodegradation: In the atmosphere, cis-l,2-dichloroethylene reacts with 
photochemically produced hydroxyl radicals resulting in half-life of 8 days. The only product 
positive identified from this reaction is formyl chloride. Photo-oxidation through reaction with 
ozone is much slower, on the order of months. Because cis-l,2-dichloroethylene absorb only a 
small amount of UV light in the environmentally significant range, direct photolysis is an 
insignificant fate process (HSDB, 1996; Howard, 1993; Howard et al., 1991). 

Hydrolysis: This isomer of 1,2-dichloroethylene contain no hydrolyzable groups 
(Howard et al., 1991) 


69 




5.4 


HUMAN EXPOSURE AND POPULATION ESTIMATES 


5.4.1 General U.S. Population 

The general population is exposed to cis-l,2-dichloroethylene in urban air and from 
contaminated drinking water from groundwater sources. For the average daily intake, HSDB 
(1996) has reported the following: air intake, assume a concentration of 68 ppt (5.4 pg); water 
intake, assume water concentration from contaminated sources of 0.23-2.7 ppb (0.5-5.4 pg) when 
drinking water is contaminated (HSDB, 1996). 

5.4.2 Occupational Exposure 

Occupational exposure to cis-l,2-dichloroethylene is expected to be through dermal 
contact with the vapor and liquids and through inhalation of contaminated air at the work place 
(HSDB, 1996). Data for occupational exposures and exposed population estimates were not 
found. 

5.4.3 Consumer Exposure 

Data for consumer exposures were not found. 



6.0 TRANS-l,2-DICHLOROETHYLENE 

6.1 CHEMICAL AND PHYSICAL PROPERTIES 

The information/data presented in this section and the supporting references were 
obtained from a retrieval from the Hazardous Substances Data Bank (HSDB, 1996). 

6.1.1 Nomenclature 


CAS No.: 156-60-5 


Synonyms: Ethylene, 1,2-dichloro-; sym-dichloroethylene 

Trade Names: No data 


6.1.2 Formula and Molecular Weight 

Structural Formula: C 2 H 2 C1 2 
Molecular Weight: 96.95 

6.1.3 Chemical and Physical Properties 


Description: Colorless, light liquid; sweetish odor (Ullmann’s Encyc Indust 

Chem, 5th Ed., Vol Al, 1985-present). 

Boiling Point: 48.0-48.5°C @ 760 mm Hg (Flick. Indust Solvents Hdbk, 1985). 


Melting Point: -50°C (Flick. Indust Solvents Hdbk, 1985). 

Density: 1.2565 @ 20°C/4°C (CRC Handbook Chem & Physics, 75th Ed, 

1994-1995). 


Spectroscopy Data: Refractive index: 1.4490 @ 15°C/D (Flick. Indust Solvents Hdbk, 

1985), IR: 3646 (Sadtler Research Laboratories Prism Collection); 
NMR: 6742 (Sadtler Research Laboratories Spectral Collection); 
MASS: 203 (Atlas of Mass Spectral Data) (Weast, 1985). 


Solubility: Soluble in alcohol, ether, acetone, benzene, and chloroform 

(Weast, 1986-97). Water solubility: 0.63 g/100 g @ 25°C (Flick. 
Indust Solvents Hdbk, 1985). 

Volatility: Vapor Pressure: 395 mm Hg at 30°C (Flick. Indust Solvents Hdbk, 

1985). 

Vapor Density: 3.67 g/1 at (bp at 760 mm Hg) (Flick. Indust 
Solvents Hdbk, 1985). 


71 


Stability: Gradually decomposed by air, light, and moisture, forming HC1 

(HSDB Scientific Review Panel; HSDB, 1996); potential phosgene 
formation (Merck Index, 10th Ed., 1983). 

Reactivity: May release explosive chloroacetylene by the contact with copper 

or copper alloys (1,2-dichloroethylene) (ITII. Tox & Hazard Indus 
Chem Safety Manual, 1988). Reacts with strong oxidizers (Sittig. 
Handbook Toxic Hazard Chem & Carcinog, 2nd Ed., 1985). 
Incompatible with alkalies, difluoromethylene dihypofluorite, and 
nitrogen tetraoxide (Sax. Danger Props Indus Mater, 6th Ed., 
1984). 

Octanol/Water 

Partition Coefficient: log Kow = 2.06 (Hansch. Log P Database, 1987). 

6.1.4 Technical Products and Impurities 

No data were identified. 

6.2 PRODUCTION AND USE 

The information/data presented in this section and the supporting references were 
obtained from a retrieval from the Hazardous Substances Data Bank during September 1996. 

6.2.1 Production 

No data concerning U.S. production, import, or export volumes were identified. 

6.2.2 Uses 

Trans-1,2-dichloroethylene is more widely used in industry than either the cis isomer or 
the commercial mixture (HSDB, 1996). It is used as a solvent for waxes, resins, and 
acetylcellulose. It is also used in the extraction of rubber, as a refrigerant, in the manufacture of 
pharmaceuticals and artificial pearls and in the extraction of oils and fats from fish and meat 
(Sittig. Handbook Toxic Hazard Chem & Carcinog, 2nd Ed., 1985). 1,2-dichloroethylenes 
obtained as byproducts are used as feed stock for the synthesis of tri- and perchloroethylene. In 
applications where dichloroethylenes could be used as solvents and for low temperature 
extraction processes, they have been replaced by methylene chloride (Ullmann’s Encyc Indust 
Chem, 5th Ed., Vol. Al, 1985-present). Although this chemical has had use as a solvent and 
chemical intermediate, it has not developed wide industrial usage in the U.S., partly because of 
its flammability (Patty. Indus Hyg and Tox, 3rd Ed., Vol. 2A, 1981-82). 


72 



6.2.3 Disposal 

A method of disposal is incineration, preferably after mixing with another combustible 
fuel. Care must be exercised to assure complete combustion to prevent the formation of 
phosgene. An acid scrubber is necessary to remove the halo acids produced (Sittig. Handbook 
Toxic Hazard Chem & Carcinog, 2nd Ed., 1985). Trans-1,2-dichloroethylene is a potential 
candidate for rotary kiln incineration at a temperature range of 820 to 1,600°C and residence 
times of seconds for liquids and gases and hours for solids. It is also a potential candidate for 
fluidized bed incineration at a temperature range of 450 to 980°C and residence times of seconds 
for liquids and gases, and longer for solids and a potential candidate for liquid injection 
incineration at a temperature range of 650 to 1,600°C and a residence time of 0.1 to 2 seconds 
(USEPA. 1981. Engineering Handbook for Hazardous Waste Incineration). This compound 
should be susceptible to removal from wastewater by air stripping (USEPA/ORD. 1980. 
Innovative and Alternative Technology Assessment Manual). 

At the time of review, criteria for land treatment or burial (sanitary landfill) disposal 
practices are subject to significant revision. Prior to implementing land disposal of waste residue 
(Including waste sludge) consult with environmental regulatory agencies for guidance on 
acceptable disposal practices (HSDB Scientific Review Panel, HSDB, 1996). 

6.3 POTENTIAL FOR HUMAN EXPOSURE 

6.3.1 Natural Occurrence 

Trans-1,2-dichloroethylene is not known to occur naturally. 

6.3.2 Occupational 

Potential occupational exposures exist in production and manufacturing facilities from 
the use of trans-l,2-dichloroethylene as a solvent and extractant. 

6.3.3 Environmental 

6.3.3.1 Environmental Releases 

Trans-1,2-dichloroethylene may be released to the environment in air emissions and 
wastewater during its production and use. Dichloroethylenes can be found as breakdown 
products from the reduction dehalogenation of common industrial solvents such as 
trichloroethylene, tetrachloroethylene, and 1,1,2,2-tetrachloroethane under aerobic high organic 
mix conditions, that may exist in landfills, aquifers, or sediment. The cis isomer is the isomer 
found most. However, it mistakenly reported as the trans isomer because EPA standard methods 
analytical procedures do not distinguish between isomers (HSDB, 1996). See Section 4.0 (1,2- 
Dichloroethylene) for more information on environmental levels. 

Air: Trans- 1,2-dichloroethylene has been identified in ambient air near production and 
manufacturing facilities from its use. 


73 



Water: Trans-1,2-dichloroethylene has been detected in drinking water, surface water, 
and groundwater. 

Other Media: Trans-1,2-dichloroethylene has been identified in the effluent of many 
manufacturing facilities, POTW effluents (and sludges), urban runoff, and sediment and soil 
samples (HSDB, 1996). 

6.3.3.2 Monitored Environmental Media Levels 

Air: The atmospheric concentration near source areas in Edison, New Jersey, was 930 ppt 
(HSDB, 1996). 

Water: Trans-1,2-dichloroethylene was found in drinking water in Miami at 1 PPB; in 
private wells in Illinois at nondetected to 64 ppb with a median of 8 ppb (HSDB, 1996). It was 
found in a groundwater plume of predominantly trichloroethylene that was believed to originate 
from an old industrial source. In Tacoma, Washington, two utility production wells had levels of 
200 ppb trans-l,2-dichloroethylene. Groundwater monitoring wells (789 wells) near a 
degreasing plant in Connecticut contained levels of this chemical ranging from 1.2 - 320.9 ppb 
(HSDB, 1996). 

Other Media: In an EPA survey of wastewater from 4,000 industrial and publicly owned 
treatment works, the highest effluent concentration among several industries was for iron and 
steel manufacturing at 3,013 ppb, with a median contamination of 2,265.9 ppb. Median 
concentrations in the effluents of other industries were: organics and plastics (14.6 ppb); 
inorganic chemicals (3.9 ppb); rubber processing (19.0 ppb); auto and other laundries (60.6 ppb); 
explosives (3.9 ppb); electronics (140.7 ppb); mechanical products (13.7 ppb); transportation 
equipment (29.3 ppb); POTWs (16.3 ppb) (Shackelford et al., Analyt Chem Acta, Vol. 146, 

1983; HSDB, 1996). In another survey of industrial occurrences, wastewater discharges had the 
following mean concentrations: metal finishing (260 ppb); photographic equipment (2,200 ppb 
maximum concentration); nonferrous metal manufacturing (75 ppb); rubber processing (150 
ppb). 

6.3.3.3 Environmental Fate and Transport 
6.3.3.3.1 Summary 

. The summary is based on the data presented in the subsequent fate and transport 
subsections. 

Fate in Terrestrial Environments: The dominant fate of 1,2-dichloroethylene released 
to surface soils is volatilization. Some 1,2-dichloroethylene may leach downward in the soil 
column because of the high water solubility and low K oc values of the two isomers. Also, 1,2- 
dichloroethylene is formed under anaerobic conditions in soil, groundwater, and sediments as a 
breakdown product from microbial reductive dehalogenation of the common industrial solvents 
trichloroethylene, tetrachloroethylene, and 1,1,2,2,-tetrachloroethane. The fate of 1,2- 


74 




dichloroethylene in subsurface soils and groundwater is slow anaerobic degradation with the 
formation of vinyl chloride as a degradation product. 

Fate in the Atmosphere: In the atmosphere, 1,2-dichloroethylene is expected to be 
present in the vapor phase rather than sorbed to particulate matter. Removal by scavenging 
during wet precipitation is expected because of the high solubility of the two isomers. The 
predominant degradation process affecting both isomers is photo-oxidation by hydroxyl radicals. 
Predicted half-lives for this reaction is 3.6 days for the trans- isomers. 

Fate in Aquatic Environments: The dominant fate of 1,2-dichloroethylene released to 
surface waters is volatilization (predicted half-life of 3 hours). Bioconcentration and sorption to 
sediments and suspended solids are not expected to be significant transport/partitioning 
processes. Although biodegradation is not expected to be a significant degradation process, any 
1,2-dichloroethylene that reaches the sediment will undergo slow anaerobic biodegradation. 

6.3.3.3.2 Transport and Partitioning 

Soil Adsorption/Mobility: The relatively low predicted soil adsorption coefficients (K oc ) 
for trans-1,2-dichloroethylene, 49, indicate that adsorption of this 1,2-dichloroethylene isomer to 
soil, sediment, and suspended solids is not a significant fate process. As a consequence, this 
isomer should show high mobility in soil (HSDB, 1996; Howard, 1993). 

Volatilization: The dominant removal mechanism for the dichloroethylene isomers in 
surface waters is volatilization. The Henry's Law constants for trans-dichloroethylene is 0.00938. 
Based on this value, the estimated half-life for volatilization of trans-dichloroethylene from a 
model river 1 m deep with a 1 m/sec current and a 3 m/sec wind speed is 3.0 hours. Similarly, 
the volatilization half-life from a 1 m deep body of water predicted from laboratory volatilization 
studies is 6.2 hours. Because of its high vapor pressure, this isomer is also expected to readily 
volatilize from soil surfaces and also from suspended particulate matter in the atmosphere 
(HSDB, 1996; Howard, 1993). 

Bioconcentration: Bioconcentration factors of 15 and 22 are predicted for cis- and trans- 
dichloroethylene, respectively, based on their respective octanol/water partition coefficients. 
Therefore, bioconcentration in aquatic organisms should not be significant and there is little 
potential for biomagnification in the food chain (HSDB, 1996; Howard, 1993). 

6.3.3.3.3 Transformation and Degradation Processes 

Biodegradation: The results of most aerobic biodegradation studies indicate that 1,2- 
dichloroethylene is recalcitrant to aerobic degradation in soil and water (i.e., half-lives on the 
order of months); however, one study reported half-lives on the order of days to weeks. Several 
studies have demonstrated that both isomers will undergo slow anaerobic biodegradation in soils 
and sediments with half-lives on the order of months or longer. Vinyl chloride is a degradation 
product (HSDB, 1996; Howard, 1993; Howard et al., 1991). 


75 




/ 


Photodegradation: In the atmosphere, trans-l,2-dichloroethylene react with 
photochemically produced hydroxyl radicals resulting in a half-life of 3.6 days. The only product 
positive identified from this reaction is formyl chloride. Photo-oxidation through reaction with 
ozone is much slower, on the order of months. Because trans-l,2-dichloroethylene absorb only a 
small amount of UV light in the environmentally significant range, direct photolysis is an 
insignificant fate process (HSDB, 1996; Howard, 1993; Howard et al., 1991). 

Hydrolysis: Trans- 1,2-dichloroethylene contains no hydrolyzable groups (Howard et al., 

1991) 

6.4 HUMAN EXPOSURE AND POPULATION ESTIMATES 

6.4.1 General U.S. Population 

The general population is exposed to trans-1,2-dichloroethylene in urban air and 
contaminated drinking water from ground water sources. 

6.4.2 Occupational Exposure 

Occupational exposure will be through dermal contact with the vapor and liquid or 
through inhalation. Data for occupational exposures and exposed population estimates were not 
found. 

6.4.3 Consumer Exposure 

Data for consumer exposures were not found. 


76 


7.0 1,1,1,2-TETRACHLOROETHANE 


7.1 CHEMICAL AND PHYSICAL PROPERTIES 

The information/data presented in this section and the supporting references were 
obtained from a retrieval from the Hazardous Substances Data Bank (HSDB, 1996). 

7.1.1 Nomenclature 

CAS No.: 630-20-6 

Synonyms: Ethane, 1,1,1,2-tetrachloro- 

Trade Names: NCI-C52459 

7.1.2 Formula and Molecular Weight 

Structural Formula: C 2 H 2 C1 4 
Molecular Weight: 167.85 

7.1.3 Chemical and Physical Properties 


Description: 

Yellowish-red liquid (NIOSH Pocket Guide Chem Haz, 1994). 

Boiling Point: 

130.5°C @ 760 mm Hg (CRC Handbook Chem & Physics, 75th 
Ed., 1994-1995). 

Melting Point: 

-70.2°C (CRC Handbook Chem & Physics, 75th Ed., 1994-1995). 

Density: 

1.4506 @ 20°C/4°C (CRC Handbook Chem & Physics, 75th Ed., 
1994-1995). 

Spectroscopy Data: 

Index of Refraction: 1.4821 @ 20°C/D (Weast, 1986-87); Mass: 
1074 (Atlas of Mass Spectral Data) (Weast, 1985). 

Solubility: 

Water solubility is 1.1 x 10 3 mg/1 @ 25°C (McKay and Shiu, 1981; 
J. Phys. Chem. Ref. Data, Vol. 19). Soluble in alcohol, ether, 
acetone, benzene, chloroform (Weast, 1986-87). 

Volatility: 

Vapor Pressure - 14 Torr at 25°C (Willing, WL. 1977. Environ Sci 
Technol, Vol. 11). 

Vapor Density - No data. 

Stability: 

Decomposes when heated and emits toxic fumes of chlorine (Sax, 
6th Ed., 1984); when in contact with flame, incandescent material, 


77 


or red hot metal surfaces, it decomposes to form hydrochloric acid, 
carbon monoxide, and carbon dioxide (Encyc. Occupat. Health and 
Safety, 1983). 

Reactivity: Mixtures of sodium-potassium alloy and bromoform, 

tetrachloroethane, or pentachloroethane can explode on standing at 
room temperature. They are especially sensitive to impact (NFPA. 
1986. Fire Protect Guide Hazard Matls, 9th Ed.) Reacts with 
dinitrogen tetraoxide; potassium hydroxide nitrogen tetroxide; 2,4- 
dinitrophenyl disulfide (NIOSH Pocket Guide Chem Haz, 1994). 

Octanol/Water 

Partition Coefficient: Log Kow = 2.66 (IARC Monographs, 1972-present) 

7.1.4 Technical Products and Impurities 

1,1,1,2-tetrachloroethane is available at 99% purity and is used for a laboratory standard 
for selected EPA methods (The Aldrich Catalog/Handbook of Fine Chemicals, 1994-95). It is 
not available in commercial quantities. 

7.2 PRODUCTION AND USE 

The information/data presented in this section and the supporting references were 
obtained from a retrieval from the Hazardous Substances Data Bank (HSDB, 1996). 

7.2.1 Production 

As of 1982, this chemical was not produced commercially in USA; no data are available 
for other years. This chemical is not produced on an industrial scale and is mainly the byproduct 
from the production of chlorinated ethanes. No data are available concerning import and export 
volumes. 

7.2.2 Uses 

1,1,1,2-tetrachloroethane is used as a solvent in cleaning, degreasing, and extraction 
processes; in manufacture of insecticides, herbicides, soil fumigants, bleaches, paints and 
varnishes and as a laboratory reagent (NRC. 1977. Drinking Water & Health; IARC 
Monograph, V.41, 1986). 1,1,1,2-tetrachloroethane is used primarily as a feedstock for the 
production of solvents such as trichloroethylene and tetrachloroethylene (Kirk-Othmer. 1991- 
present. Encyc Chem Tech, 4th Ed., Vol 1). 


78 








7.2.3 Disposal 


1,1,1,2-tetrachloroethane is a potential candidate for fluidized bed incineration at a 
temperature range of 450 to 980°C and residence times of seconds for liquids and gases and 
longer for solids; for rotary kiln incineration at a temperature range of 820 to 1,600°C and 
residence times of seconds for liquids and gases and hours for solids; and for liquid injection 
incineration at a temperature range of 650 to 1,600°C and a residence time of 0.1 to 2 seconds 
(USEPA. 1981. Engineering Handbook for Hazardous Waste Incineration. EPA 68-03-3025). 
Incineration is a method of disposal, preferably after mixing with another combustible fuel. Care 
must be exercised to assure complete combustion to prevent the formation of phosgene. An acid 
scrubber is necessary to remove the halo acids produced. Recommendable methods are 
incineration and evaporation. Not recommendable method: discharge to sewer. 

At the time of review, criteria for land treatment or burial (sanitary landfill) disposal 
practices are subject to significant revision. Prior to implementing land disposal of waste residue 
(including waste sludge), consult with environmental regulatory agencies for guidance on 
acceptable disposal practices (HSDB Scientific Review Panel; HSDB, 1996). 

7.3 POTENTIAL FOR HUMAN EXPOSURE 

7.3.1 Natural Occurrence 

Available data do not indicate that 1,1,1,2-tetrachloroethane occurs naturally. 

7.3.2 Occupational 

1,1,1,2-tetrachloroethane is not produced on an industrial scale but is formed as an 
incidental byproduct. Potential occupational exposure would occur from exposure to air 
emissions or contact with the vapor or liquid in the workplace. 

7.3.3 Environmental 

7.3.3.1 Environmental Releases 

According to available data, it appears that 1,1,1,2-tetrachloroethane is currently not 
produced in the U.S. However, since the chemical may be formed incidentally during the 
manufacture of other chlorinated ethanes, it may be released into the environment as air 
emissions or in wastewater (HSDB, 1996). It has not been confirmed if this chemical is currently 
used in the U.S. However, if used, environmental releases as a result of use would be expected. 

7.3.3.2 Monitored Environmental Media Levels 

Ain Field studies were conducted in Arizona and California to better characterize the 
abundance of selected chemicals in the atmosphere. Average daily dosages from exposure to 
haloethane, including 1,1,1,2-tetrachloroethane, was determined to be 142 pg/day (Singh, H.B. et 
ah, 1981; Atmos. Environ. Vol. 15, No. 4; HSDB, 1996). 1,1,1,2-tetrachloroethane was not 


79 


detected in two rural/remote sites in the U.S. For 602 urban/suburban sites in the U.S., a median 
level of 2.2 ppt and a maximum level of 63 ppt were found. In source areas, 43 sites/samples in 
the U.S., the mean concentration was 0.071 ppt and the maximum level 3.1 ppt. However, 
1,1,1,2-tetrachloroethane was not detected in over 75 percent of the samples (Brodzinsky and 
Singh, SRI Contract 68-02-34; Class and Ballschmiter, 1986, Chemosphere, Vol. 15; HSDB, 
1996). 


Water: In the U.S. Groundwater Supply Survey, 1,1,1,2-tetrachloroethane was not 
detected (detection limit 0.2 ppb) in the drinking water of 945 supplies where groundwater was 
the source (Westrick et al., 1984; J. Amer. Water Works Assoc., Vol. 76; HSDB, 1996). 

Other Media: Wastewater was analyzed in a survey conducted by the EPA of 4,000 
industrial and publicly owned treatment works. 1,1,1,2-tetrachloroethane was identified in the 
discharges from several industrial categories. The median concentrations reported as follows: 
organics and plastic (27.4 ppb); inorganic chemicals (14.8 ppb); and electronics (272.6 ppb) 
(Shackelford, W.M. et al., 1983, Analyt. Chem. Acta., Vol. 146; HSDB, 1996). 

7.3.3.3 Environmental Fate and Transport 

7.3.3.3.1 Summary 

The summary is based on the data presented in the subsequent fate and transport 
subsections. 

Fate in Terrestrial Environments: The dominant fate of 1,1,1,2-tetrachloroethane 
released to surface soils is volatilization. Because of its moderate mobility in soils, 
tetrachloroethylene introduced into soil (e.g., landfills) has the potential to migrate through the 
soil into groundwater. 

Fate in the Atmosphere: In the atmosphere, 1,1,1,2-tetrachloroethane is expected to be 
present primarily in the vapor phase rather than sorbed to particulates because of its moderate 
vapor pressure. Removal by scavenging during wet precipitation is expected because of the 
moderate solubility of 1,1,1,2-tetrachloroethane in water (1,100 mg/L). The major degradation 
process affecting vapor phase 1,1,1,2-tetrachloroethane is photo-oxidation by hydroxyl radicals 
and the chlorine radicals formed by the hydroxyl radical reaction (half-life on the order of years). 
Due to its persistence, 1,1,1,2-tetrachloroethane will disperse over long distances and slowly 
diffuse into the stratosphere where it would be rapidly degraded. 

Fate in Aquatic Environments: The dominant fate of 1,1,1,2-tetrachloroethane released 
to surface waters is volatilization (predicted half-life of hours). Bioconcentration and sorption to 
sediments and suspended solids are not expected to be significant transport/partitioning 
processes. 


80 




73.3.3.2 Transport and Partitioning 


Soil Adsorption/Mobility: A K oc of 93 is predicted for 1,1,1,2-tetrachloroethane based 
on its measured water solubility. An experimentally determined K oc for 1,1,1,2-tetrachloroethane 
is reported to be 399. Based on the predicted and measured K oc s, 1,1,1,2-tetrachloroethane is 
expected to exhibit moderate mobility and may leach slowly to the groundwater particularly in 
soils with low organic content (HSDB, 1996). 

Volatilization: The dominant removal mechanism for 1,1,1,2-tetrachloroethane in 
surface waters is volatilization. The half-life will depend on wind and mixing conditions and is 
estimated to range from 4 to 11 hours in rivers, lakes, and ponds based on laboratory 
experiments. Because of its moderate vapor pressure (14 torr at 25 degrees C) and relatively low 
soil adsorption coefficient (K oc of 93 to 399), 1,1,1,2-tetrachloroethane is expected to volatilize 
from dry soil surfaces and also from suspended particulate matter in the atmosphere (HSDB, 
1996). 


Bioconcentration: No experimental data are available on the bioconcentration of 1,1,1,2- 
tetrachloroethane. A bioconcentration factor of 12 is predicted for 1,1,1,2-tetrachloroethane 
based on its measured water solubility of 1,100 mg/L. Actual BCFs measured in fish studies are 
less than 10 for structurally similar halogenated aliphatic compounds. Therefore, 
bioconcentration in aquatic organisms should not be significant and there is little potential for 
biomagnification in the food chain (HSDB, 1996). 

7.3.3.33 Transformation and Degradation Processes 

Biodegradation: Little information is available on the biodegradability of 1,1,1,2- 
tetrachloroethane. Based on the results of a river die-away test for 1,1,1,2-tetrachloroethane and 
several studies examining the biodegradability of 1,1,1-trichloroethane, 1,1,1,2-tetrachloroethane 
is estimated to undergo biodegradation at a slow rate. The estimated half-lives are one to six 
months under aerobic conditions and 4 to six months under anaerobic conditions (Howard et al., 
1991). 


Photodegradation: Based upon an estimated rate constant for the vapor phase photo¬ 
oxidation reaction with photochemically produced hydroxyl radicals, the half-life of 1,1,1,2- 
tetrachloroethane in the atmosphere is 550 days. No data are readily available on the photolysis 
of 1,1,1,2-tetrachloroethane (HSDB, 1996). 

Hydrolysis: Hydrolysis of 1,1,1,2-tetrachloroethane is not significant at environmental 
temperatures and pHs; the half-life for this process (at 25 C, pH 7) is 46.8 years (HSDB, 1996). 

7.4 HUMAN EXPOSURE AND POPULATION ESTIMATES 

7.4.1 General U.S. Population 

Potential exposure, if any, to the general population would probably be through inhalation 
of ambient air contaminated with 1,1,1,2-tetrachloroethane (HSDB, 1996). 


81 




7.4.2 Occupational Exposure 

Data are not available for the estimated occupationally exposed populations. 

7.4.3 Consumer Exposure 

According to Kirk-Othmer (1991), 1,1,1,2-tetrachloroethane is used primarily as a 
feedstock for the production of solvents such as trichloroethylene and tetrachloroethylene 
(HSDB, 1996). The IARC Monographs in 1986 have reported use in the manufacture of 
products such as paints and varnishes. It has not been confirmed if this use is current or if these 
products are/were consumer or industrial products (HSDB, 1996). 


7.5 CHAPTER SUMMARY 

Table 7-1 summarizes the findings of 1,1,1,2-tetrachloroethane. 


Table 7-1. 1,1,1,2-Tetrachloroethane Summary 



Estimates 

Support 

Uses 

Many solvent applications; chemical 
intermediate 

Recent information 

Production 

As of 1982, not produced in U.S.; no other 
data are available 


Releases 

No available data 


Properties/Fate 

Volatile; water soluble; no significant 
bioconcentration; moderate mobility 

Recent information 

Media Levels 

Air: 0.012 pg/m 3 - median value at 

602 urban/suburban sites 

Water: Non detect (detection limit = 0.2 

ppb) in 945 groundwater supplies 


General Population 

Exposure 

No available data 


Special Population 

Exposures 

No available data 



82 













8.0 


1,1-DICHLOROETHANE 


8.1 CHEMICAL AND PHYSICAL PROPERTIES 

The information/data presented in this section and the supporting references were 
obtained from a retrieval from the Hazardous Substances Data Bank (HSDB, 1996). 

8.1.1 Nomenclature 

CAS No.: 75-34-3 

Synonyms: Ethane, 1,1-dichloro-; ethylidene chloride; ethylidene dichloride 

Trade Names: NCI-C04535 

8.1.2 Formula and Molecular Weight 

Molecular Formula: C 2 H 4 CT 

Molecular Weight: 98.97 

8.1.3 Chemical and Physical Properties 


Description: 

Oily liquid, chloroform-like odor, taste as of chloroform 


(Merck Index, 11th Ed., 1989); colorless liquid (Sax. Danger 
Props Idus Mater, 6th Ed., 1984); colorless, oily liquid, 
chloroform-like odor (NIOSH Pocket Guide Chem Haz, 1994); 
aromatic ethereal odor (Sax. Hawley’s Condensed Chem Diet, 
11th Ed., 1987). 

Boiling Point: 

57.3°C (Merck Index, 11th Ed., 1989). 

Melting Point: 

-96.9°C (CRC Handbook Chem & Physics, 75th Ed., 1994- 
1195). 

Density: 

1.175 @ 20°C/4°C (Merck Index, 11th Ed., 1989). 

Spectroscopy Data: 

Index of Refraction: 1.4167 @ 20°C (Merck Index, 11th Ed., 
1989); Sadtler Reference Number: 3205 (IR, prism); J118 
(NMR) (Weast, 1979); Mass: 68 (National Bureau of Standards 
EPA-NIH Mass Spectra Data Base) (Weast, 1985). 

Solubility: 

0.55 g/100 ml water at 20°C; soluble in ethanol, ethyl ether 
(Patty. Indus Hyg & Tox, 3rd Ed., Vol 2A, 2B, 2C, 1981-82) 

Volatility: 

Vapor Pressure: 3.44 (air = 1) (Sax. Danger Props Indus 

Mater, 6th Ed., 1984). 


83 


Vapor Density: 234 torr at 25°C (Patty. Indus Hyg & Tox, 3rd 
Ed., Vol 2A, 2B, 3C, 1981-82). 

Stability: No data. 

Reactivity: Reacts with strong oxidizers, strong caustics (NIOSH Pocket 

Guide Chem Haz, 1994). 


Octanol/Water 

Partition Coefficient: Log Kow = 1.9 (ITC/USEPA. Information Review #209 

(Draft) Chloroethanes, 1980). 

8.1.4 Technical Products and Impurities 

1,1-dichloroethane is produced as reagent grade, 99.7% pure, with the following 
impurities: ethyl chloride 0.02%, butylene oxide 0.08%, trichloroethylene 0.08%, ethylene 
dichloride 0.01%, unknown 0.14% (expressed as volume percentage by weight of sample 
(ITC/USEPA. 1980. Information Review #209). 

8.2 PRODUCTION AND USE 

The information/data presented in this section and the supporting references were 
obtained from a retrieval from the Hazardous Substances Data Bank (HSDB, 1996). 

8.2.1 Production 

No information was identified for U.S. production, import, or export volumes. 

8.2.2 Uses 

1,1-dichloroethane is used as a solvent for plastics, oils, and fats; cleaning agent; 
degreaser; in rubber cementing; as a fumigant and insecticide spray; in fabric spreading; in fire 
extinguishing; and in medication: formerly used as an anesthetic (Browning. 1965. Tox & 
Metab Indus Solv). It is also used as an extractant for heat-sensitive substances (NIOSH OSHA. 
1981. Occupat Health Guide Chem Hazards). Other uses include as a coupling agent in 
antiknock gasoline; in paint, varnish and paint removers; metal degreasing; and in ore flotation 
(Verschueren. 1983. Handbook Environ Data Org Chem). 1,1-dichloroethane is usually used as 
an intermediate in the production of 1,1,1 -trichloroethane by thermal chlorination or 
photochlorination and in the production of vinyl chloride (Kirk-Othmer, 1991-present). 

8.2.3 Disposal 

Generators of waste containing this contaminant (i.e., EPA hazardous waste number 
U076) must conform with USEPA regulations in storage, transportation, treatment, and disposal 
of waste (40 CFR 240-280, 300-306, 702-799). 1,1-dichloroethane may be disposed of by 
atomizing in a suitable combustion chamber equipped with an appropriate effluent gas cleaning 


84 







device (NIOSH OSHA. 1981. Occupat Health Guide Chem Hazards). It is a potential candidate 
for liquid injection incineration, with a temperature range of 650 to 1,600°C and a residence time 
of 0.1 to 2 seconds; for rotary kiln incineration, with a temperature range of 820 to 1,600 °C and 
a residence time of seconds; and for fluidized bed incineration, with a temperature range of 450 
to 980°C and a residence time of seconds (USEPA. 1981. Engineering Handbook for Hazardous 
Waste Incineration). The following wastewater treatment technologies have been investigated 
for 1,1-dichloroethane: concentration process: stripping, solvent extraction, activated carbon, 
and resin adsorption (USEPA. 1982. Management of Hazardous Waste Leachate. EPA 
Contract No. 68-03-2766). 

8.3 POTENTIAL FOR HUMAN EXPOSURE 

8.3.1 Natural Occurrence 

There are no known natural sources of 1,1-dichloroethane; however, it has been reported 
that 1,1,1-trichloroethane is biodegraded to 1,1-dichloroethane in anaerobic environments such as 
landfills (ATSDR, 1990). 

8.3.2 Occupational 

In addition to members of the general populations living near emission point sources and 
hazardous waste sites, human exposure to 1,1-dichloroethane is expected to be highest among 
certain occupational groups (ATSDR, 1990). These groups are workers in the chemical and 
allied products industry (ATSDR, 1990). 

8.3.3 Environmental 

8.3.3.1 Environmental Releases 

The primary disposition of 1,1-dichloroethane in the environment is the result of 
production, storage, consumption, transport, and disposal from its use as chemical intermediate, 
solvent, finish remover, and degreaser (ATSDR, 1990). Releases from industrial processes are 
almost exclusively to the atmosphere. 1,1-dichloroethane has been detected generally at low 
levels in ambient air, surface water, groundwater, drinking water, and human breath. 
Concentrations are largest in environmental media near source areas (ATSDR, 1990). Another 
source of this chemical in the environment is the reduction (biotic or abiotic) of 1,1,1- 
trichloroethane to 1,1 -dichloroethane in groundwater (HSDB, 1996). 

Air: The majority (99 percent) of all releases of 1,1-dichloroethane to the environment 
are emissions to the atmosphere (ATSDR, 1990). Releases from the production of 1,1,1- 
trichloroethane and 1,2-dichloroethane account for approximately 52 percent and 35 percent, 
respectively of these releases (ATSDR, 1990). Approximately 52,000 kg of 1,1-dichloroethane 
are released to the air from POTWs (ATSDR, 1990). 

Water: Releases of 1,1-dichloroethane to surface waters from industrial solvent use and 
from POTWs are approximately 2,000 kg/yr (ATSDR, 1990). The largest sources of these 


85 




releases are believed to be from its use as a cleaning solvent or chemical intermediate and from 
POTWs (ATSDR, 1990). Approximately 1,000 kg/yr of 1,1-dichloroethane are released in the 
effluents of POTWs (ATSDR, 1990). 

Other Media: Releases to land from solvent use and POTWs were estimated at 6,000 kg 
in 1978 (ATSDR, 1990). According to ATSDR (1990), approximately 4,000 kg/yr of 1,1- 
dichloroethane are released to land as sludge from POTWs. 

8.33.2 Monitored Environmental Media Levels 

Air: Atmospheric levels of 1,1-dichloroethane have been detected at urban, rural, and 
industrial sites across the U.S. The reported median concentration is 55 ppt (ATSDR, 1990). In 
the urban/suburban parts of the U.S., reported concentrations were 61 ppt (median value) and 100 
ppt (maximum values) for the analysis of 455 samples (HSDB, 1996). The concentrations in 
source areas (101 samples) were 11 ppt (median value) and 1,400 ppt (maximum value) (HSDB, 
1996). 

Water: Data summarized from the EPA STORET data base in 1982 have shown 
concentrations for 1,1-dichloroethane ranging from <10 ppb (not detected) to 1,900 ppb 
(ATSDR, 1990). The highest reading was from the upper Mississippi River Basin; however, the 
reported monitoring results indicated that in surface water the levels were mostly <10 ppb. 

According to a study summarizing groundwater data from numerous State agencies, 18 
percent of monitored drinking water wells contained 1,1-dichloroethane; the highest reported 
concentration in wells was 11,300 ppb and a maximum surface concentration of 0.2 ppb 
(ATSDR, 1990; HSDB, 1996). In Iowa, 127 wells from 58 public water supplies contained 1,2- 
dichloroethane residues 1 to 24 ppb (HSDB, 1996). 

Finished water supplies in the U.S. from groundwater sources that were tested for EPA 
contaminants had a maximum concentration of 4.2 ppb; detectable levels of 1,1-dichloroethane 
was found in 10.8 percent of 158 non-random samples. Groundwater samples taken from 178 
hazardous waste disposal sites contained an average concentration of 0.31 ppm with a maximum 
concentration of 56.1 ppm and had a frequency of 18 percent (ATSDR, 1990). 

Other Media: Data for levels in soil were not found. The reported mean concentration 
was 33 ppt for oysters obtained from the Mississippi River delta (HSDB, 1996). Information 
were not found for ambient concentrations of 1,1-dichloroethane in soil, current disposal of 
waste products containing this chemical in landfills, foods, plants, fish, or animals (HSDB, 1996; 
ATSDR, 1990). 


86 












8.3.33 Environmental Fate and Transport 
8.3.3.3.1 Summary 


The summary is based on the data presented in the subsequent fate and transport sections. 

Fate in Terrestrial Environments: The dominant fate of 1,1 -dichloroethane released to 
surface soils is volatilization. Because of its high mobility in soils, 1,1-dichloroethane 
introduced into soil (e.g., landfills) has the potential to migrate through the soil into groundwater. 
Biodegradation under anaerobic conditions in soil and groundwater may occur at a relatively 
slow rate (half-lives on the order of months or longer). 

Fate in the Atmosphere: In the atmosphere, 1,1-dichloroethane is expected to be present 
in the vapor phase rather than sorbed to particulate matter. Removal of 1,1-dichloroethane 
during wet precipitation is expected because of its relatively high water solubility. 1,1- 
Dichloroethane will degrade by reaction with photochemically produced hydroxyl radicals. 
Because photo-oxidation is not a rapid process (predicted half-lives ranging from 10 to 100 
days), considerable dispersion of 1,1-dichloroethane in the atmosphere may occur. 

Fate in Aquatic Environments: The dominant fate of 1, 1 -dichloroethane released to 
surface waters is volatilization (predicted half-life of 1 to 10 days). Bioconcentration, 
biodegradation, and sorption to sediments and suspended solids are not expected to be significant 
fate processes. 

8.3.33.2 Transport and Partitioning 

Soil Adsorption/Mobility: The very low predicted soil adsorption coefficients (K oc ) for 
1,1-dichloroethane (K oc of 43) indicates that sorption of 1,1-dichloroethane to soil, sediment, and 
suspended solids is not a significant fate process. As a consequence, these isomers should show 
high mobility in soil (HSDB, 1996). 

Volatilization: The dominant removal mechanism for the 1,1-dichloroethane isomers in 
surface waters is volatilization. The half-life will depend on wind and mixing conditions and is 
estimated to range from 1 to 10 days in rivers, lakes, and ponds based on laboratory experiments. 
Because of its high vapor pressure and relatively low soil adsorption coefficient, 1,1- 
dichloroethane is expected to volatilize rapidly from soil surfaces and also from suspended 
particulate matter in the atmosphere (HSDB, 1996). 

Bioconcentration: A bioconcentration factor of 1.3 is predicted for 1,1-dichloroethane 
based on the reported water solubility of 5,500 mg/L. Therefore, bioconcentration in aquatic 
organisms should not be significant and there is little potential for biomagnification in the food 
chain (HSDB, 1996). 


87 




i 


8.3.3.3.3 Transformation and Degradation Processes 

Biodegradation: The results of aerobic biodegradation studies indicate that 1,1- 
dichloroethane is recalcitrant to aerobic degradation in soil and water (i.e., half-lives on the order 
of months). Although no studies examining the anaerobic biodegradation of 1,1-dichloroethane 
are available, the estimated half-life under anaerobic conditions has been estimated to range from 
months to years (HSDB, 1996; Howard et ah, 1991). 

Photodegradation: Based on measured rate data for the vapor phase reaction with 
hydroxyl radicals, the estimated half-life of 1,1-dichloroethane in the troposphere ranges from 10 
to 100 days (HSDB, 1996; Howard et al., 1991). 

Hydrolysis: No information specifically addressing the hydrolytic half-life of 1,1- 
dichloroethane is available. Considering the volatility of 1,1-dichloroethane from water and the 
fact that the hydrolytic half-lives of structurally similar chlorinated ethanes are on the order of 
months to years, indicates that hydrolysis is not an important fate process (HSDB, 1996; Howard 
et ah, 1991). 

8.4 HUMAN EXPOSURE AND POPULATION ESTIMATES 

8.4.1 General U.S. Population 

The primary route of exposure for the general population to 1,1-dichloroethane is the 
inhalation of air contaminated with this chemical. An additional potential route of exposure is 
ingestion of 1,1-dichloroethane contaminated drinking water. Specifically, persons near 
industrial facilities and hazardous waste may be potentially exposed from inhalation of ambient 
air and ingestion of drinking water (ATSDR, 1990). EPA has identified 1,1 -dichloroethane in 
248 of the 1,177 NPL sites; the number of sites evaluated for this chemical was not reported 
(ATSDR, 1990). The frequency of these sites within the U.S. are presented in Figure 8-1. 

The U.S. EPA assumed median ambient air concentration of 55 ppt and an average 
inhalation rate of 20 m 3 /day and estimated the average inhalation exposure to 1,1-dichloroethane 
from the general population to be 4 pg/day (ATSDR, 1990). 

8.4.2 Occupational Exposure 

Populations potentially exposed in the workplace in the early 1980s were estimated by 
NIOSH to have ranged from 715 to 1,957 workers (ATSDR, 1990). Occupational exposures are 
primarily the result of the use of 1,1-dichloroethane as a chemical intermediate, solvent, and a 
component of fumigant formulations (ATSDR, 1990). 

8.4.3 Consumer Exposure 

No data were found for consumer exposure estimates. 


88 











FREQUENCY 


FFFff 




I TO 2 SITES 

II TO 20 SITES 



3 TO 
OVER 


lO SITES 
20 SITES 


Figure 8-1. Frequency of NPL Sites with 1,1-Dichloroethane Contamination (Source: ATSDR 
1990) 


89 


















































































































































































































































































































































































8.5 CHAPTER SUMMARY 


Table 8-1 summarizes the findings of 1,1-dichloroethane. 


Table 8-1. 1,1-DichIoroethane Summary 



Estimates 

Support 

Uses 

Many solvent uses; fumigant; chemical 
intermediate; degreaser 

Well documented 

Production 

No available information 


Releases 

Predominantly air - 52,000 kg released to air 
from POTWs 

ATSDR (1990) 

Properties/Fate 

Volatile; slightly soluble in water; no 
significant bioconcentration or 
biodegradation expected 


Media Levels 

Air: urban/suburban - 0.332 pg/m' 

(median) 

Water: surface water <10 ppb to 1,900 ppb 
Groundwater: varies 

1 to 24 ppb (Iowa; 127 wells) 

455 samples 

General Population 

Exposure 

Primarily through air or potentially 
contaminated groundwater 

Air = 4 pg/d 

ATSDR (1990) 

Special Population 

Exposures 

Chemical and allied product workers 

ATSDR (1990) 


90 












SECTION C. METABOLITES OF TRICHLOROETHYLENE AND PARENT 
COMPOUNDS 


9.0 CHLORAL 

9.1 CHEMICAL AND PHYSICAL PROPERTIES 

The information/data presented in this section and the supporting references were 
obtained from a retrieval from the Hazardous Substances Data Bank (HSDB, 1996) and IARC 
(1995). 

9.1.1 Nomenclature 

CAS No.: 75-87-6 

Synonyms: 2,2,2-trichloroacetaldehyde; acetaldehyde, trichloro-; anhydrous 

chloral; trichloroacetaldehyde; trichloroethanol 

Trade Name: Grasex 


9.1.2 Formula and Molecular Weight 

Structural Formula: C 2 HCl 3 -0 

Molecular Weight: 147.40 


9.1.3 Chemical and Physical Properties 


Description: 

Boiling Point: 
Melting Point: 
Density: 


Colorless, oily liquid with an irritating odor (Encyc. Occupat. 
Health & Safety, 1983). 

97.8°C @ 760 mm Hg (Merck Index, 10th Ed., 1983). 

-57.5°C (Merck Index, 10th Ed., 1983). 

1.5121 @ 20°C/4°C (Weast. Hdbk. Chem. & Phys., 67th Ed., 
1986-87). 


Spectroscopy Data: Index of refraction: 1.45572 @ 20°C/D (Weast. Hdbk. Chem. & 

Phys., 67th Ed., 1986-87); IR: 4626, IR: 4426 (Sadtler Research 
Laboratories Prism Collection); IR: 6507 (Coblentz Society 
Spectral Collection); UV: 5-3 (Organic Electronic Spectral 
Data); Mass: 814 (Atlas of Mass Spectral Data) (Weast. CRC 
Hdbk. Data Organic CPDS., Vol. I, II, 1985) 


91 


Solubility: Highly soluble in water; soluble in alcohol, ether (Merck Index, 

10th Ed., 1983); chloral hydrate is extremely soluble in water 
(825 g/100 g water (Seidell, A. (1941) Solubilities of Organic 
Compounds); soluble in chloroform (Condensed Chem. 
Dictionary, 10th Ed., 1981). 

Volatility: Vapor Pressure: 35 mm Hg @ 20°C (Encyc. Occupat. Health & 

Safety, 1983; I ARC, 1995). 

Vapor Density: 5.1 (air = 1) (Patty. Indus. Hyg. & Tox, 1981- 
1982). 

Stability: Unstable (Goodman (1985) Pharm. Basis Therap., 7th Ed.). 


Reactivity: Forms chloral hydrate when dissolved in water and forms chloral 

alcoholate when dissolved in alcohol (Merck Index, 10th Ed., 
1983). 


Octanol/Water 

Partition Coefficient: No data. 

9.1.4 Technical Products and Impurities 

Chloral is produced in a technical grade with a minimum of 94% purity (Hawley (1981) 
Condensed Chem. Dictionary, 10th Ed.). Instead of water, various alcohols can be added to 
chloral to form hemiacetals. Chloral alcoholate and chloral betaine are simple adducts and 
laboratory anesthetic alpha-chloralose is a complex adduct. Chloral is an unstable oil that does 
not lend itself well to pharmaceutical formulations; therefore, in medicine it was introduced in 
the form of chloral hydrate (Goodman (1985) Pharm. Basis Therap, 7th Ed.) The typical 
impurities (max.) are as follows: water, 0.06%; 2,2-dichloroethane, 0.3%; 2,2,3-trichlorobutanal, 
0.01%; hydrogen chloride, 0.06%; and chloroform (IARC, 1995). 

9.2 PRODUCTION AND USE 

The information/data presented in this section and the supporting references were 
obtained from a retrieval from the Hazardous Substances Data Bank (HSDB, 1996) and IARC 
(1995). 

9.2.1 Production 

The principal use of chloral in the U.S. was in the manufacture of DDT. According to 
IARC (1995), when the use of DDT was banned in the U.S. in 1972, the demand for chloral in 
the U.S. rapidly declined. DDT is still produced in the U.S. for use in tropical countries (IARC, 
1995). 


- U.S. Production: (1969) 2.83 x 10 10 g; (1975) 2.27 x 10 10 g (SRI). 


92 




- Import Volumes: 


(1984) 1.02 x 10 8 g (Bureau of the Census. U.S. Imports for 
Consumption and General Imports, 1984). 

- Export Volumes: (1972 and 1975) negligible. 

9.2.2 Uses 

Chloral is used in the spraying and pouring of polyurethanes (NRC, 1977); as a chemical 
intermediate for the herbicide trichloroacetic acid and chloral hydrate (HSDB, 1996); used to 
induce swelling of starch granules at room temperature (Kirk-Othmer, 1978-present); and as an 
intermediate in DDT and other insecticides, including: methoxychlor, dichlorvos, naled, and 
trichlorofon (Sittig. (1985) Handbook Toxic hazard Chem & Carcinog, 2nd Ed.; IARC, 1995). 
Estimated use in the U.S. in 1975 was in the manufacture of DDT (40%); methoxychlor, 
dichlorvos, and naled (10%); and miscellaneous other applications (50%) (IARC, 1995). 

9.2.3 Disposal 

Chloral is a potential candidate for liquid injection incineration at a temperature range of 
650 to 1,600°C and a residence time of 0.1 to 2 seconds; for rotary kiln incineration at a 
temperature range of 820 to 1,600°C and residence times of seconds for liquids and gases, and 
hours for solids; and for fluidized bed incineration at a temperature range from 450 to 980°C and 
residence times of seconds for liquids and gases, and longer for solids. (USEPA (1981) 
Engineering Handbook for Hazardous Waste Incineration). 

At the time of review, criteria for land treatment or burial (sanitary landfill) disposal 
practices are subject to significant revision. Prior to implementing land disposal of waste residue 
(including waste sludge), consult with environmental regulatory agencies for guidance on 
acceptable disposal practices (HSDB Technical Review Panel; HSDB, 1996). 

9.3 POTENTIAL FOR HUMAN EXPOSURE 

9.3.1 Natural Occurrence 

Chloral is not known to occur as a natural product (IARC, 1995). 

9.3.2 Occupational 

Exposure to chloral is thought to be primarily via inhalation and dermal contact with the 
vapor (HSDB, 1996). Chloral has been detected in the work environment during spraying and 
casting of polyurethane foam, identified as an auto-oxidation product of trichloroethylene during 
extraction of vegetable oil, and also identified at the output of etching chambers in 
semiconductor processing (IARC, 1995). 


93 



9.3.3 Environmental 


9.3.3.1 Environmental Releases 

Chloral may be released to the environment from the synthesis of methoxychlor and 
DVPP, and also from wood processing plants in the chlorination portion of the bleaching process 
(HSDB, 1996). It is a reactive intermediate metabolite of trichloroethylene (IARC, 1995). 

9.3.3.2 Monitored Environmental Media Levels 
Air: No data. 

Water: Chloral is formed during aqueous chlorination of humic substances and amino 
acids (IARC, 1995). It may therefore occur in drinking water as a result of chlorine disinfection 
of raw waters containing natural organic substances. The concentration of chloral measured in 
drinking water in the U.S. is summarized in Table 9-1. 

Chloral was reported in the drinking water supplies of several U.S. cities as follows: 
Philadelphia, PA - 5 pg/1; Seattle, WA - 3.5 pg/1; Cincinnati, OH - 2 pg/1; Terrebonne Parish, LA 
- 1 pg/1; New York City, NY - 0.02 pg/1; Grand Forks, ND - 0.01 pg/1 (HSDB, 1996). In surface 
water samples taken from water of New Orleans/Baton Rouge, chloral was reported at a mean 
concentration of 1.0 pg/1 (HSDB, 1996). 

Chloral has also been detected in the spent chlorination liquor from bleaching of sulfite 
pulp after oxygen treatment at concentrations of <0.1 to 0.5 g/ton of pulp. Trace amounts have 
also been reported from photocatalytic degradation of trichloroethylene in water (IARC, 1995). 

Other Media: Chloral is a reactive intermediate metabolite of trichloroethylene (IARC, 

1995). 


Table 9-1. Concentrations of Chloral (As Chloral Hydrate) 
in Drinking Water in the United States 


Water Type (Location) 

Concentration (pg/L) 

Tap water (reservoir) 

7.2-18.2 

Surface, reservoirs, lake, and groundwater 

1.7-3.0 

Tap water 

0.01-5.0 

Distribution system 

0.14-6.7 

Surface water 

6.3-28 


Source: IARC, 1995. 


94 









9.3.3.3 Environmental Fate and Transport 
9.3.3.3.1 Summary 


Fate in Terrestrial Environments: The dominant fate of chloral released to soils is 
rapid hydrolysis by soil water to form chloral hydrate. Volatilization is likely to be important 
only in the event of a spill onto relatively dry soil. 

Fate in the Atmosphere: Chloral should react rapidly with the moisture in air to form 
chloral hydrate. Although photo-oxidation by hydroxyl radicals will likely occur to some extent, 
the reaction rate is much slower than for hydrolysis; the half-life for the vapor phase reaction of 
chloral with photochemically produced hydroxy radicals is estimated to be 10.8 hours. 

Fate in Aquatic Environments: The dominant fate of any chloral released to water is 
rapid hydrolysis to form chloral hydrate. Although this hydrolysis reaction is reversible, the 
equilibrium constant favors the formation of chloral hydrate (27,000 to 1). Chloral is thus 
essentially removed from the water. Volatilization, sorption to suspended solids, and 
bioconcentration are not expected to be significant. 

9.3.3.3.2 Transport and Partitioning 

Soil Adsorption/Mobility: No data are available concerning the sorption of chloral to 
soil. However, since chloral reacts rapidly with water to form chloral hydrate, it should also react 
rapidly with soil moisture. Since chloral hydrate is extremely soluble in water (8,250 g/L) and is 
not expected to sorb to soil, chloral hydrate has the potential to leach through soils (HSDB, 

1996). 


Volatilization: Chloral has a relatively high vapor pressure (35 torr at 25 degrees C) and 
should therefore volatilize rapidly from dry surfaces. Chloral reacts rapidly with water to form 
chloral hydrate thus precluding any significant volatilization of chloral from water (HSDB, 
1996). 


Bioconcentration: No data are available concerning the bioconcentration of chloral. 
However, since chloral reacts rapidly with water to form chloral hydrate, bioconcentration would 
not be expected to be a significant fate process. Since chloral hydrate is extremely soluble in 
water (8,250 g/L), bioconcentration in aquatic organisms should not be significant for chloral 
hydrate (HSDB, 1996). 

9.3.3.33 Transformation and Degradation Processes 

Biodegradation: No data are available concerning the biodegradability of chloral. 
However, since chloral reacts rapidly with water to form chloral hydrate, biodegradation would 
not be expected to be a significant fate process. 

Photodegradation: The half-life for the vapor phase reaction of chloral with 
photochemically produced hydroxy radicals is estimated to be 10.8 hours. No data are available 


95 






on the photolytic sensitivity of chloral. However, acetaldehyde has a UV absorption maximum at 
293 nm which suggests that chloral will also absorb some UV light (HSDB, 1996). 

Hydrolysis: Chloral reacts exothermically with water to form chloral hydrate. Because 
the equilibrium constant for this reaction is 3.6 x 10' 5 , very little chloral will remain in solution 
(HSDB, 1996) 

9.4 HUMAN EXPOSURE AND POPULATION ESTIMATES 

9.4.1 General U.S. Population 

The general population can be exposed to chloral during its production and use, from 
drinking chlorinated water, and from pharmaceutical use (IARC, 1995). 

9.4.2 Occupational Exposure 

Results of the National Occupational Exposure Survey conducted between 1981 and 1983 
indicate that 2,757 employees in the U.S. were potentially exposed to chloral (IARC, 1995). The 
estimate was based on a survey of companies and did not involve measurements of actual 
exposure. 

9.4.3 Consumer Exposure 

No data concerning consumer exposure were found. 

9.5 CHAPTER SUMMARY 

Table 9-2 summarizes the findings of chloral. 


96 





Table 9-2. Chloral Summary 



Estimates 

Support 

Uses 

Chemical intermediate for manufacture of 
pesticides; used in spraying and pouring of 
polyurethanes 

Well documented 

Production 

2.3 x 10 7 kg 

1975 data 

Releases 

No available data 


Properties/Fate 

Soluble in water; rapid hydrolysis to chloral 
hydrate; no significant bio-concentration 
expected 


Media Levels 

Air: no data 

Drinking water supplies: six U.S. cities - 
0.02 ug/1 to 5 mg/1 


General Population 

Exposure 

No available data 


Special Population 

Exposures 

2,757 employees potentially exposed 

Data from early 1980s 


97 













10.0 


CHLORAL HYDRATE 


10.1 CHEMICAL AND PHYSICAL PROPERTIES 

The information/data presented in this section and the supporting references were 
obtained from a retrieval from the Hazardous Substances Data Bank (HSDB, 1996). 

10.1.1 Nomenclature 


CAS No. 

302-17-0 

Synonyms: 

1,1,1 -trichloro-2,2-dihydroxy ethane; 2,2,2-trichloro-1,1 -ethanediol; 
trichloroacetaldehyde hydrate; trichloroacetaldehyde monohydrate; 
trichloroethylidene glycol; 2,2,2-trichloroethane-l,l-diol 

Trade Names: 

Kessodrate, Noctec, Phaldrone, Sontec, Chloralvan, Chloralex 


10.1.2 Formula and Molecular Weight 

Molecular Formula: C 2 H 3 C1 3 02 

Molecular Weight: 165.42 

10.1.3 Chemical and Physical Properties 


Description: 

Transparent, colorless crystals (Sax, 1984); aromatic, 


penetrating and slightly acrid odor; slightly bitter, caustic taste 
(Merck Index, 11th Ed., 1989). 

Boiling Point: 

96.3°C @ 764 mm Hg (decomp) (CRC Handbook Chem. & 
Physics, 1991-1992). 

Melting Point: 

-57°C (Merck Index, 11th Ed., 1989). 

Density: 

1.908 @ 20°C/4°C (CRC Handbook Chem. & Physics, 1991- 
1992). 


Spectroscopy Data: IR: 5423 (Coblentz Society Spectral Collection); NMR: 10362 


Solubility: 

(Sadtler Research Laboratories Spectral Collection); Mass: 

1054 (Atlas of Mass Spectral Data) (Weast, 1985); intense 
mass spectral peaks: 82 m/z, 111 m/z, 146 m/z (Pfleger, 1985). 

2.4 g/ml water @ 0°C; 14.3 g/ml water @ 40°C; 8.3 g/ml water 
at 25°C. Sparingly soluble in turpentine, petroleum ether, 
benzene, toluene, carbon tetrachloride; 1 g/68 g carbon 
disulfide; 1 g/1.3 ml alcohol; 1 g/1.4 ml olive oil; freely soluble 


98 








in acetone, methyl ethyl ketone; 1 g/2 ml chloroform; 1 g/1.5 
ml ether; 1 g/0.5 ml glycerol (Merck Index, 11th Ed., 1989). 


Volatility: 


No data. 


Stability: 


Slowly volatilizes on exposure to air (Merck Index, 11th Ed., 
1989). Aqueous solutions of chloral hydrate decomposed 
rapidly when exposed to ultraviolet light, with the formation of 
hydrochloric acid, trichloroacetic acid, and formic acid. A 1% 
solution lost about 5% of its strength after storage at room 
temperature for 20 weeks; aqueous solutions are likely to 
develop mold growth (Martindale. Extra Pharmacopeia, 28th 
Ed., 1982). 


Reactivity: 


No data. 


Octanol/Water 

Partition Coefficient: log Kow = 0.99 (Hansch. Log P Database, 1987) 

10.1.4 Technical Products and Impurities 

Dosage forms for chloral hydrate are the following: capsules: 250 and 500 mg, and 1 g; 
elixir: 500 mg/5 ml; suppositories: 325, 500, and 650 mg; syrup: 250 and 500 mg/5 ml 
(Remington’s Pharm. Sci., 17Ed., 1985). Noctec capsules contain 250 or 500 mg chloral hydrate 
per capsule; Noctec syrup contains 500 mg chloral hydrate per 5 cc (AHFS drug Information 92 
Plus Suppl’s). Chloral hydrate is produced in technical and USP grades (Sax, 1987). For 
chloropent injection; intravenous anesthetic; each ml contains chloral hydrate 42.5 mg; 
magnesium sulfate 21.2 mg; pentobarbital 8.86 mg; ethyl alcohol 14.25%; propylene glycol 
33.8%; and purified water, qs (for cattle and horses) (Vet Pharm. & Biolog., 1982-1983). 

Chloral hydrate capsules contain not less than 95.0% and not more than 110.0% of the labeled 
amount of chloral hydrate; chloral hydrate syrup contains not less than 95.0% and not more than 
110.09% of the labeled amount of chloral hydrate (USPC. USP XXII & NF XVII 1990, Plus 
Suppl’s). 

10.2 PRODUCTION AND USE 

The information/data presented in this section and the supporting references were 
obtained from a retrieval from the Hazardous Substances Data Bank (HSDB, 1996). 

10.2.1 Production 


U.S. Production: (1972) 1.14 x 10 10 g (anhydrous chloral); (1975) 5.9 x 10 8 g 

(SRI). 


99 


Import Volume: 


(1972) 2.83 x 10 7 g; (1975) 4.8 x 10 7 g (SRI); (1984) 5.41 x 10 6 
g; 4.67 x 10 12 g (Bureau of the Census. U.S. Imports for 
Consumption and General Imports, 1984; 1986). 

Export Volume: No data. 

10.2.2 Uses 

Chloral hydrate is used in medication as a hypnotic and sedative (Merck Index, 11th 
Ed., 1989; IARC, 1995). It is also used as a rubefacient in topical preparations (AHFS Drug 
Information 92 Plus Suppl’s); veterinary medication (Vet Pharm. & Biolog., 1982-1983); and as 
a glue peptizing agent (Kirk-Othmer, 1980). 

10.2.3 Disposal 

Chloral hydrate is a waste chemical stream constituent which may be subjected to 
ultimate disposal by controlled incineration, preferably after mixing with another combustible 
fuel. Care must be exercised to assure complete combustion to prevent the formation of 
phosgene; an acid scrubber is necessary to remove the halo acids produced (USEPA. 1981. 
Engineering Handbook of Hazardous Waste Leachate). Solvent extraction is a wastewater 
treatment technology that has been investigated for chloral hydrate (USEPA. 1982. Engineering 
Handbook of Hazardous Waste Leachate). 

10.3 POTENTIAL FOR HUMAN EXPOSURE 

10.3.1 Natural Occurrence 

Chloral hydrate is not known to occur as a natural product (IARC, 1995). 

10.3.2 Occupational 

Specific information concerning potential for occupational exposure were not found. 

10.3.3 Environmental 

10.3.3.1 Environmental Releases 

Specific data on environmental releases of chloral hydrate were not found. 

10.3.3.2 Monitored Environmental Media Levels 
Air: No data. 

Water: Chloral hydrate may occur in drinking water as a result of chlorine disinfection 
of raw waters containing natural organic substances. The concentration of chloral measured in 
drinking water (as chloral hydrate) in the U.S. is summarized in Section 9, Table 9-1. 


100 











Other Media: Chloral hydrate has been detected in human milk (HSDB, 1996). Data 
were not available in HSDB (1996) on the mechanism whereby the breast milk became 
contaminated. 

10.3.3.3 Environmental Fate and Transport 

10.3.3.3.1 Summary 

The summary is based on the data presented in the subsequent fate and transport 
subsections. 

Fate in Terrestrial Environments: Since chloral hydrate is very soluble in water 
(8,250 g/L), it is not expected to sorb to soil and thus has the potential to leach through soils. No 
information is available on the biodegradation of chloral hydrate. 

Fate in the Atmosphere: Any chloral hydrate released to the atmosphere is expected to 
be readily scavenged during precipitation events. Chloral hydrate may also undergo photolysis, 
but the available data are not adequate to determine its relative importance. 

Fate in Aquatic Environments: Because of its very high water solubility, chloral 
hydrate is not expected to volatilize, sorb to suspended solids or sediments, or bioconcentrate. 

No information is available on the biodegradation of chloral hydrate. 

10.3.3.3.2 Transport and Partitioning 

Soil Adsorption/Mobility: No data are available concerning the sorption of chloral 
hydrate to soil. However, since chloral hydrate is very soluble in water (8,250 g/L), it is not 
expected to sorb to soil and thus has the potential to leach through soils (HSDB, 1996). 

Volatilization: Although vapor pressure data for chloral hydrate are not readily 
available, chloral hydrate has been reported to slowly volatilize from surfaces when exposed to 
air. Because of its very high water solubility, volatilization from water is not expected to be 
significant (HSDB, 1996). 

Bioconcentration: No data are available concerning the bioconcentration of chloral 
hydrate. However, since chloral hydrate is very soluble in water (8,250 g/L), bioconcentration in 
aquatic organisms should not be significant (HSDB, 1996). 


10.3.3.3.3 Transformation and Degradation Processes 

Biodegradation: No information is available on the biodegradation of chloral hydrate 
(HSDB, 1996). 

Photodegradation: Although no studies have apparently been published that 
quantitatively have examined direct atmospheric photolysis of chloral hydrate, a 1 percent 


101 





aqueous solution of chloral hydrate was reported to have lost 5 percent of its strength after 
storage for 20 weeks at room temperature. Hydrochloric acid, trichloroacetic acid, and formic 
acid were formed as products (HSDB, 1996). 

Hydrolysis: Hydrolysis is not expected to be a significant fate process for chloral 

hydrate. 

10.4 HUMAN EXPOSURE AND POPULATION ESTIMATES 

Human exposure to chloral hydrate can occur during its production and use, from 
pharmaceutical use, and from drinking chlorinated water (IARC, 1995). Specific exposure data 
and data on estimates of exposed populations were not found. The general population may be 
potentially exposed from ingestion of drinking water contaminated with chloral hydrate. The 
occupational population may be exposed in the workplace during production and use. The 
consumer population may be potentially exposed from use of pharmaceuticals. 

10.5 CHAPTER SUMMARY 

Table 10-1 summarizes the findings of chloral hydrate. 


Table 10-1. Chloral Hydrate Summary 



Estimates 

Support 

Uses 

Pharmaceutical 

Well documented 

Production 

5.9 x 10 5 kg 

1975 data 

Releases 

No available data 


Properties/Fate 

Water soluble; no significant 
bioconcentration expected; no information 
on biodegradation 


Media Levels 

No available data 


General Population 

Exposure 

No available data 


Special Population 

Exposures 

No available data 



102 


















11.0 


MONOCHLOROACETIC ACID 


11.1 CHEMICAL AND PHYSICAL PROPERTIES 

The information/data presented in this section and the supporting references were 
obtained from a retrieval from the Hazardous Substances Data Bank (HSDB, 1996). 

11.1.1 Nomenclature 


CAS No.: 

79-11-8 

Synonyms: 

Acetic acid; chloro-; alpha-chloroacetic acid; chloracetic acid; 
chloroethanoic acid; monochloroacetic acid; monochloroethanoic acid 

Trade Names: 

NCI-C60231 


11.1.2 Formula and Molecular Weight 

Molecular Formula: C 2 H 3 C10 2 

Molecular Weight: 94.50 

11.1.3 Chemical and Physical Properties 


Description: 

Colorless or white crystals (Merck Index, 11th Ed., 1989). 


Characteristic penetrating odor similar to vinegar. 

Boiling Point: 

All three forms (alpha, beta, gamma) boil at 189° C (Merck 
Index, 11th Ed., 1989). 

Melting Point: 

Exists in three physical modifications: alpha 63° C; beta 55- 
56° C; gamma 50° C (Merck Index, 11th Ed., 1989). 

Density: 

1.4043 @ 40° C/4° C (Gardner’s Chem Synonyms, Trade 
Names, 1987). 


Spectroscopy Data: Index of Refraction: 1.4351 @ 55° C/D; Sadtler Ref. Number: 

2094 (IR, Prism (Weast, 1988-89); IR: 5567 (Coblentz Society 


Solubility: 

Spectral Collection) (Weast, 1985); NMR: 128 (Sadtler 
Research Laboratories Spectral Collection) (Weast, 1985); 
Mass; 196 (Weast, 1985). 

Very soluble in water, slightly soluble in chloroform (Weast, 
1988-89); Soluble in acetone, carbon disulfide (Weast, 1979); 
soluble in benzene (Merck Index, 1989); soluble in ethanol, 
diethyl ether (Worthing, Pesticide Manual, 1979); soluble in 
carbon tetrachloride (Encyc. Occupat. Health & Safety, 1983). 


103 


Volatility: 


Stability: 

Reactivity: 


Octanol/Water 

Partition Coefficient: log Kow = 0.22 (Hansch, 1981) 

11.1.4 Technical Products and Impurities 

Monochloroacetic acid is produced in technical and medicinal grades with 99.5% 
purity. Data were not available for impurities. 

11.2 PRODUCTION AND USE 

The information/data presented in this section and the supporting references were 
obtained from a retrieval from the Hazardous Substances Data Bank (HSDB, 1996). 

11.2.1 Production 

U.S. Production: (1978) 3.50 x 10 10 g (SRI); (1982) probably greater than 6.81 x 10 6 g 

(SRI); Chemical Int. For sodium carboxymethyl cellulose, 60%; for 
herbicides, 30%; for other derivatives (e.g., glycine, thioglycolic acid, 
pharmaceuticals, and indigoid dyes), 10% (SRI, 1979). 

Import Volumes: (1978) 1.25 x 10 10 g (SRI); (1982) 1.35 x 10 10 g (SRI). 

11.2.2 Uses 

Monochloroacetic acid is used as a chemical intermediate for pharmaceuticals (e.g., 
vitamin A); chemical intermediate for indigoid dyes; and as a herbicide (Merck Index, 1989). It 
is also used as a preservative, bacteriostat, intermediate in production of synthetic caffeine; 
carboxymethyl cellulose; ethyl chloracetate; glycine; scariosine; thioglycolic acid; EDTA; 2,4-D; 
2,4,5-T (Hawley’s Condensed Chem. Diet., 11th Ed., 1987). It has also been recommended as a 
defoliant (Pesticide Manual, 4th Ed., 1974, p.106). 

11.2.3 Disposal 

No data were identified. 


Vapor Pressure: 1 mm Hg @ 43.0° C (Patty, Indus. Hyg. & 
Tox., 3rd Ed., 1981-82). 

Vapor Density: 3.26 (air = 1) (Sax, 1984). 

No data. 

Highly reactive; chemically reacts with ammonia to form 
glycine and with aniline to form a precursor for indigo dyes 
(Encyc. Occupat. Health & Safety, 1983). 


104 


11.3 


POTENTIAL FOR HUMAN EXPOSURE 


11.3.1 Natural Occurrence 

No information on the natural occurrence of chloracetic acid was found. 

11.3.2 Occupational 

No specific information on potential for occupational exposure of chloracetic acid was 

found. 

11.3.3 Environmental 
11.3.3.1 Environmental Releases 

Chloracetic acid may enter the environment in emissions and wastewater from its 
production and use as a chemical intermediate primarily in the manufacture of chlorophenoxy 
herbicides and carboxymethyl cellulose. Such releases of the chemical would be limited to 
industrial settings (HSDB, 1996). Chloroacetic acid has been used as a pre-emergent herbicide 
and defoliant, and if it is still used for these applications, its use would constitute an emission 
source and ground contamination of a more general nature (HSDB, 1996). 

Total Toxic Release (TRI) releases for years 1987 to 1994 are shown in Table 11-1. 
The receiving media are air, water, land, and for underground injection, POTW transfer, and 
other transfer. These releases are reported from manufacturing and processing facilities. Only 
certain facilities are required to report, and therefore may not capture all releases. 


Table 11-1. Release of Chloroacetic Acid (lbs/yr) 


Year 

Number of 

Reporting 

Facilities 

Fugitive Air 
Releases 

Stack Air 
Releases 

Surface 

Water 

Release 

Underground 

Injection 

Land 

Disposal 

POTW 

Transfer 

Other 

Transfers 

Total 

1987 

34 

24229 

4383 

29956 

280 

0 

1380 

4010 

64272 

1988 

37 

21660 

5159 

850 

10 

0 

10727 

9406 

47849 

1989 

35 

20616 

4229 

1524 

10 

0 

9717 

4096 

40227 

1990 

37 

20660 

4759 

1691 

0 

0 

1785 

6779 

35711 

1991 

36 

60745 

446920 

1696 

0 

123675 

3279 

6444 

642795 

1992 

31 

10778 

1024 

3199 

0 

0 

1792 

3147 

19971 

1993 

29 

5796 

767 

8719 

0 

750 

1433 

2219 

19713 

1994 

32 

5983 

710 

10178 

0 

950 

1015 

6259 

25127 


Source: TRI, 1996. 


105 




















11.3.3.2 Monitored Environmental Media Levels 


Air: Data were not found for monitored levels in air. 

Water: Between the spring of 1988 and the winter of 1989, grab samples were 
collected at the clearwell effluents (after disinfection) from 35 treatment facilities and analyzed 
by gas chromatography/mass spectroscopy (GC/MS). The concentration of monochloroacetic 
acid was <1.0 to 1.2 pg/L (U.S. EPA, 1994). Chloroacetic acid was also found in a study where 
concentrated humic acid from a coastal North Carolina lake was chlorinated (U.S. EPA, 1994). 

Other Media: Data were not found for monitored levels in other media. 

11.3.3.3 Environmental Fate and Transport 

11.3.3.3.1 Summary 

The summary is based on the data presented in the subsequent fate and transport 
subsections. 

Fate in Terrestrial Environments: The dominant fate of chloroacetic acid released to 
or into soils is biodegradation. Although no soil biodegradation studies with chloroacetic acid 
have been reported, studies with wastewater and river water inocula indicate that biodegradation 
in soil will be a relatively rapid process. This ready biodegradability should minimize the 
possibility of any significant leaching of chloroacetic acid into groundwater. 

Fate in the Atmosphere: Because of its high water solubility and slow rates of photo¬ 
oxidation and photolysis, any chloroacetic acid released into the atmosphere will likely be 
scavenged during precipitation events before any significant photodegradation occurs. 

Fate in Aquatic Environments: The dominant fate of chloroacetic acid released to 
surface waters is biodegradation (predicted half-life of days). Bioconcentration and sorption to 
sediments and suspended solids are not expected to be significant transport/partitioning 
processes. 

11.3.3.3.2 Transport and Partitioning 

Soil Adsorption/Mobility: The relatively low predicted soil adsorption coefficient (log 
K oc ) for chloroacetic acid (0.08) indicates that adsorption to soil, sediment, and suspended solids 
is not a significant fate process. As a consequence, chloroacetic acid has the potential for high 
mobility in soil; however, the extent of migration will be minimized because of the ready 
biodegradability of chloroacetic acid (HSDB, 1996; U.S. EPA, 1996). 

Volatilization: The very low predicted Henry's Law constant for chloroacetic acid 
(<10‘ 7 atm-m 3 /mol) indicates that minimal volatilization is expected from water bodies. Because 
of its relatively low vapor pressure (<1 torr), minimal volatilization from soil surfaces is 
expected (HSDB, 1996; U.S. EPA, 1996). 


106 











Bioconcentration: A bioconcentration factor of 0.86 is predicted for chloroacetic acid 
based on its very low measured log octanol/water partition coefficient of 0.22. Therefore, 
bioconcentration in aquatic organisms should not be significant and there is little potential for 
biomagnification in the food chain (HSDB, 1996; U.S. EPA, 1996). 

11.3.3.3.3 Transformation and Degradation Processes 

Biodegradation: Chloroacetic acid is expected to undergo ultimate biodegradation in 
aerobic environmental settings with a half-life on the order of days. Degradation under anaerobic 
conditions is expected to proceed more slowly with a predicted half-life on the order of weeks. 

In laboratory tests using sewage or acclimated sludge inocula, chloroacetic acid readily 
undergoes biodegradation with greater than 70-90 percent degradation being reported in 5-10 
days. The results of river water studies indicate 73 percent mineralization (i.e., conversion to 
carbon dioxide) in 8-10 days (HSDB, 1996; U.S. EPA, 1996; Howard et al., 1991). 

Photodegradation: Photolysis in the atmosphere or in aquatic environments is 
expected to proceed very slowly with predicted half-lives on the order of months to years. 
Chloroacetic acid does not appreciably absorb UV light above 290 nm and thus will not directly 
photolyze. The presence of sensitizers such as p-cresol and tryptophan that generate superoxide 
radicals has been shown to increase the rate of photodechlorination by up to 16-fold. Based on 
the estimated reaction rate constant of chloroacetic acid with hydroxyl radicals, the estimated 
half-life of chloroacetic acid in the atmosphere is on the order of weeks to months (HSDB, 1996; 
Howard et al., 1991). 

Hydrolysis: Based upon the results of darkened controls during photolysis experiments, 
the half-life of chloroacetic acid is on the order of years (HSDB, 1996; Howard et al., 1991) 

11.4 HUMAN EXPOSURE AND POPULATION ESTIMATES 

Data were not found for human exposure and population estimates. 

11.5 CHAPTER SUMMARY 

Table 11-1 summarizes the findings of monochloroacetic acid. 


107 



Table 11-2. Monochloroacetic Acid Summary 



Estimates 

Support 

Uses 

Chemical intermediate; herbicide 

Well documented 

Production 

6.81 x 10 3 kg/yr 

1982 data 

Releases 

25,127 lbs - all media 

1994 TRI data 

Properties/Fate 

Very soluble in water; no significant 
bioconcentration or biodegradation expected 


Media Levels 

Air: no available data 

Water samples from treatment facilities - 
<1.0 to 1.2 ug/1 

35 facilities 

General Population 

Exposure 

No available data 


Special Population 

Exposures 

No available data 



108 

















12.0 DICHLOROACETIC ACID 


12.1 CHEMICAL AND PHYSICAL PROPERTIES 

The information/data presented in this section and the supporting references were 
obtained from I ARC Monographs, Volume 63, 1995. 

12.1.1 Nomenclature 

CAS No.: 79-43-6 

Synonyms: Bichloracetic acid; DCA; CDA (acid); DCAA; dichloracetic acid; 

dichlorethanoic acid; dichloroethanoic acid; 2,2-dichloroethanoic acid 

12.1.2 Formula and Molecular Weight 

Molecular Formula: C 2 H 2 C1 2 0 2 

Molecular Weight: 128.94 

12.1.3 Chemical and Physical Properties 


Description: 

Colorless to slightly yellowish liquid with a pungent acid-like 
odor (Merck Index, 1989; Hoechst Chemicals, 1990). 

Boiling Point: 

194°C 

Melting Point: 

13.5°C 

Density: 

1.5634 @20°C/4°C 

Spectroscopy Data: 

Infrared (prism [2806]; grating [36771]), nuclear magnetic 
resonance (proton [116], C-13 [500], and mass spectral data 
have been reported (Sadtler Research Laboratories, 1980; 

I ARC, 1995). 

Solubility: 

Soluble in water, acetone, ethanol, and diethyl ether; also 
soluble in ketones, hydrocarbons, and chlorinated hydrocarbons 
(IARC, 1995). In aqueous solution, dichloroacetic acid and 
dichloroacetate exist as an equilibrium mixture, the proportions 
of each depending primarily on the pH of the solution. The pK a 
of dichloroacetic acid is 1.48 @ 25°C. 

Volatility: 

Vapor Pressure - 0.19 mbar (19 Pa) @ 20°C (Hoechst 
Chemicals, 1990). 

Vapor Density - No data. 


109 


Reactivity: 


Highly corrosive and attacks metals; releases hydrogen chloride 
gas (see IARC, 1992) when heated (Hoechst Chemicals, 1990). 


Octanol/Water 

Partition Coefficient: log P, 0.92 (Hansch, 1995) 

12.1.4 Technical Products and Impurities 

Dichloroacetic acid is available commercially at a purity of 99% with a maximum of 
0.3% water (Hoechst Chemicals, 1990; Spectrum Chemical Mfg Corp., 1994) 

12.2 PRODUCTION AND USE 

12.2.1 Production 

Figures for the production and use of dichloroacetic acid in the U.S. or throughout the 
world are not available (IARC, 1995). 

12.2.2 Uses 

Dichloroacetic acid is presently of little economic importance. Its acid chloride and 
methyl ester, however, are used as intermediates in the manufacture of agrochemicals and the 
pharmaceutical, chloramphenicol (IARC, 1995). Dichloroacetic acid is also a starting material 
for the production of glyoxylic acid, dialkyloxy and diaryloxy acids, and sulfonamides. The 
compound is used as a test reagent for analytical measurements during the manufacture of 
polyethylene terephthalate and as a medical disinfectant, in particular as a substitute for 
formaldehyde (IARC, 1995). It has been considered for use in the treatment of lactic acidosis, 
diabetes mellitus, hyperlipoproteinaemia, and several other disorders; however, it has never been 
marketed for any of these purposes (Merck Index, 1989). 

12.2.3 Disposal 

No information concerning disposal methods for dichloroacetic acid was identified. 

12.3 POTENTIAL FOR HUMAN EXPOSURE 

12.3.1 Natural Occurrence 

Dichloroacetic acid is not known to occur as a natural product. 

12.3.2 Occupational 

No specific information concerning the potential for human exposure in an occupational 
setting was found. 


110 










12.3.3 


Environmental 


12.3.3.1 Environmental Releases 

No information concerning environmental releases of dichloroacetic acid was found. 

12.3.3.2 Monitored Environmental Media Levels 
Air: No data available. 

Water: Dichloroacetic acid is produced as a by-product during aqueous chlorination of 
humic substances and therefore it may occur in drinking water after chlorine disinfection of raw 
waters containing natural substances (I ARC, 1995). The concentrations of dichloroacetic acid 
measured in various water sources and reported in various studies are summarized in Table 12-1. 
According to IARC (1995), it has been identified as a major chlorinated by-product of the 
photocatalytic degradation of tetrachloroethylene in water and a minor by-product of the 
degradation of trichoroethylene. 


Other Media: In humans, dichloroacetic acid is a reactive intermediate metabolite of 
trichloroethylene and an end-metabolite of 1,1,1,2-tetrachloroethane. Dichloroacetic acid has 
also been reported as a biotransformation product of methoxyflurane (IARC, 1995) and 
dichlorvos (IARC, 1995). It may occur in the tissues and fluids of animals treated with 
dichlorvos for helminthic infections (IARC, 1995). 


Table 12-1. Concentrations of Dichloroacetic Acid in Water 


Water Type (Location) 

Concentration Range (pg/L) 

Drinking Water (chlorinated tap water (USA) 

63.1 - 133 

Drinking Water (chlorinated surface, reservoir, lake, and groundwater) (USA) 

5.0-7.3 

Chlorinated Surface Water (USA) 

9.4 - 23 

Chlorinated Drinking Water (USA) 

8-79 

Swimming Pool (Germany) 

indoors: 0.2 - 10.6 
open air: 83.5 - 181.0 3 

Surface Water (downstream from a paper mill) &Austria) 

<3 - 522 

Biologically Treated Kraft Pulp Mill Effluent (Malaysia) 

14-18 


3 The higher levels found in open-air swimming pools may be due to the input of organic material by swimmers. 
Source: IARC, 1995. 


Ill 











12.3.3.3 Environmental Fate and Transport 

No information is readily available on the environmental fate and transport of 
dichloroacetic acid. However, its environmental fate is expected to be similar to that of 
monochloroacetic acid and trichloroacetic acid. The environmental fate and transport of 
monochloroacetic acid and trichloroacetic acid are discussed in Sections 11.3.3.3 and 13.3.3.3, 
respectively. 

12.4 HUMAN EXPOSURE AND POPULATION ESTIMATES 

12.4.1 General U.S. Population 

The general population is potentially exposed to dichloroacetic acid through the 
ingestion of chlorinated drinking water, contact with surface water contaminated with this 
chemical, and chlorinated water in swimming pools. 

12.4.2 Occupational Exposure 

The National Occupational Exposure Survey conducted between 1981 and 1983 
indicated that 1,592 employees in the United States were potentially exposed to dichloroacetic 
acid in 39 facilities (IARC, 1995). 

12.4.3 Consumer Exposure 

Data were not found on consumer exposure to dichloroacetic acid. 

12.5 CHAPTER SUMMARY 

Table 12-2 summarizes the findings of dichloroacetic acid. 


Table 12-2. Dichloroacetic Acid Summary 



Estimates 

Support 

Uses 

Chemical intermediate 


Production 

No available data 


Releases 

No available data 


Properties/Fate 

Water soluble 


Media Levels 

Water: 5-133 ug/1 


General Population 

Exposure 

No available data 


Special Population 

Exposures 

1,592 employees potentially exposed 

Data from early 1980s 


112 


















13.0 TRICHLOROACETIC ACID 


13.1 CHEMICAL AND PHYSICAL PROPERTIES 

The information/data presented in this section and the supporting references were 
obtained from a retrieval from the Hazardous Substances Data Bank (HSDB, 1996). 

13.1.1 Nomenclature 


CAS No.: 

70-03-9 

Synonyms: 

Acetic acid; trichloro-, 'TCA’, trichloroethanoic acid 

Trade Names: 

AMCHEM Grass Killer, Nata, Natal 


13.1.2 Formula and Molecular Weight 

Structural Formula: C 2 HC1 3 0 2 

Molecular Weight: 163.40 

13.1.3 Chemical and Physical Properties 


Description: 

Colorless to white, crystalline solid; sharp, pungent odor 


(NIOSH Pocket Guide Chem. Haz., 1994). 

Boiling Point: 

195.5°C (CRC Handbook Chem. & Physics, 76th Ed., 1995- 
96). 

Melting Point: 

-57.5°C (CRC Handbook Chem. & Physics, 76th Ed., 1995- 
96). 

Density: 

1.6126 @ 64°C (CRC Handbook Chem. & Physics, 76th Ed., 
1995-96). 

Spectroscopy Data: 

Index of refraction: 1.4603 @ 61°C (CRC Handbook Chem. & 
Physics, 76th Ed., 1995-96); IR: 2376 (Coblentz Society 
Spectral Collection); UV: 1-6 (Organic Electronic Spectral 
Data); NMR: 6 (Sadtler Research Laboratories Spectral 
Collection); Mass: 1026 (Atlas of Mass Spectral Data) (Weast, 
CRC Handbook Data Organic CPDS, Vol. I, II, 1985). 

Solubility: 

In water - 1306 g/100 g @ 25°C; in methanol - 2143 g/100 g @ 
25°C; in ethyl ether - 617 g/100 g @ 25°C; in acetone - 850 
g/100 g @ 25°C; in benzene - 201 g/100 g @ 25°C1 in o-xylene 
- 110 g/100 g @ 25°C (Kirk-Othmer. Encyc. Chem. Tech., 4th 
Ed., Vol. 1, 1991-present); soluble in ethanol, ethyl ether; 


113 


slightly soluble in carbon tetrachloride (CRC Handbook Chem. 
& Physics, 76th Ed., 1995-96). 

Volatility: Vapor Pressure - 1 mm Hg @ 51.0°C (solid) (CRC Handbook 

Chem. & Physics, 72nd Ed., 1991-1992). 

Stability: Stable in the absence of moisture (Pesticide Manual, 8th Ed., 

1987); 2-year shelf life minimum, may cake however 
(Herbicide Hdbk, 5th Ed., 1983). 

Reactivity: Reacts with moisture, iron, zinc, aluminum, strong oxidizers 

(Note: decomposes on heating to form phosgene and hydrogen 
chloride. Corrosive to metals.) (NIOSH Pocket Guide Chem. 
Haz., 1994). 


Octanol/Water 

Partition Coefficient: No data. 


13.1.4 Technical Products and Impurities 

Trichloroacetic acid is produced in a technical grade (chemically pure: a grade 
designation signifying a minimum of impurities, but not 100% purity) and a USP grade 
(Hawley’s Condensed Chem. Diet., 12th Ed., 1993). 

13.2 PRODUCTION AND USE 


The information/data presented in this section and the supporting references were 
obtained from a retrieval from the Hazardous Substances Data Bank (HSDB, 1996). 

13.2.1 Production 


- U.S. Production: (1975) greater than 3.60 x 10 6 g; (1976) greater than 2.27 x 

10 6 g (SRI). 

- Import Volumes: (1984) 3.67 x 10 9 g/chloroacetic acid (Bureau of the 

Census. U.S. Imports for Consumption and General 
imports, 1984). 


- Export Volumes: 


13.2.2 Uses 


(1984) 8.60 x 10 9 g (Halogenated Hydrocarbons, Bureau of 
the Census. U.S. Exports, 1984). 


Trichloroacetic acid is used as a chemical intermediate for the production of ethylene 
glycol bis(trichloroacetate) and herbicides, sodium trichloroacetate and monuron-TCA; and used 
as a lab reagent for biological applications (SRI). TCA has been used as an astringent and 
antiseptic, and polymerization catalyst (Kirk-Othmer. Encyc. Chem. Tech., 4th Ed., Vol. 1, 


114 








1991-present). About 21,000-23,000 t/a of the TCA sodium salt are used worldwide as a 
selective herbicide (Ullmann’s Encyc. Indust. Chem., 5th Ed., 1985-present). 

13.2.3 Disposal 

Reverse osmosis is a wastewater treatment technology that has been investigated for 
trichloroacetic acid (USEPA, 1982, Management of Hazardous Waste Leachate). After mixing, 
transfer into a drum and fill with water for drainage after 24 hours (Tox. & Hazard. Indus. Chem. 
Safety Manual, 1988). 

At the time of review, criteria for land treatment or burial (sanitary landfill) disposal 
practices are subject to significant revision. Prior to implementing land disposal of waste residue 
(including waste sludge), consult with environmental regulatory agencies for guidance on 
acceptable disposal practices (HSDB Scientific Review Panel; HSDB, 1996). 

13.3 POTENTIAL FOR HUMAN EXPOSURE 

13.3.1 Natural Occurrence 

Trichloroacetic acid is not known to occur naturally (IARC, 1995). 

13.3.2 Occupational 

The probable routes of occupational exposure are dermal contact and inhalation. 
Trichloroacetic acid is the major end metabolite of trichloroethylene and tetrachloroethylene in 
humans and has been used as a biological marker of exposure to these compounds (IARC, 1995). 
Additionally, it is a metabolite of 1,1,1-trichoroethane and 1,1,1,2-tetrachloroethane and chloral 
hydrate is rapidly oxidized to trichloroacetic acid in humans (IARC, 1995). 

13.3.3 Environmental 

13.3.3.1 Environmental Releases 

The production of trichloroacetic acid and its use in organic synthesis, medicine, 
pharmaceuticals, and as a herbicide may result in its release to the environment through 
wastestreams (HSDB, 1996). 

13.3.3.2 Monitored Environmental Media Levels 
Air: No data. 

Water: The concentrations of trichloroacetic acid in water are presented in Table 13-1. 

Other Media: Trichloroacetic acid has been detected in the following foods(IARC, 

1995): 


115 


Table 13-1. Concentrations of Trichloroacetic Acid in Water 


Water Type (Location) 

Concentration Range (pg/L) 

Chlorinated Tap Water (USA) (drinking water) 

33.6- 161 

Chlorinated Drinking Water (USA) 

4.23 - 53.8 

Raw Water (USA) 

95-2,120 

Chlorinated Surface, Reservoir, Lake, and Groundwaters 
(USA) 

4.0-6.0 

Chlorinated Surface Water (USA) 

7.4 - 22 

Chlorinated Drinking Water (USA) 

15-64 

Raw Water (USA) 

60- 1,630 


Source: I ARC, 1995. 

• Seed of wheat, barley, and oats after treatment with trichloroacetic acid as 
postemergent herbicide; 

• Fruits and vegetables after irrigation with trichloroacetic acid contaminated water 
(trace levels); and 

• Field bean pods and seeds (0.13 to 0.43 mg/kg) 

Concentration of trichloracetic acid was in irrigation water after the application of the 
sodium salt (herbicide) to control canary grass on the banks of dry canals in the State of 
Washington. The levels measured ranged from 53 to 297 ppb (HSDB, 1996). 

13.3.3.3 Environmental Fate and Transport 

13.3.3.3.1 Summary 

The summary is based on the data presented in the subsequent fate and transport 
subsections. 

Fate in Terrestrial Environments: The dominant fate of trichloroacetic acid released 
onto or into soils is biodegradation. Studies with wastewater and soil indicate that aerobic 
biodegradation in soil will occur within weeks to months depending on the soil type, moisture 
and temperature. However, the low reported K oc for trichloroacetic acid indicates that 
trichloroacetic acid should have high mobility in soil and, therefore, significant leaching to 
groundwater could occur, particularly in sandy soils. 

Fate in the Atmosphere: Because of its moderate vapor pressure (<1 mm Hg at 25 
degrees C), trichloroacetic acid should exist predominantly in the vapor phase in the atmosphere. 
Vapor phase trichloroacetic acid is degraded in the atmosphere by reaction with photochemically 
produced hydroxyl radicals; the half-life for this reaction is estimated to be about 31 days. 


116 
















Fate in Aquatic Environments: The dominant fate of trichloroacetic acid released into 
surface waters is biodegradation (predicted weeks to months). Bioconcentration, sorption to 
sediments and suspended solids, and volatilization are not expected to be significant 
transport/partitioning processes. 

13.3.3.3.2 Transport and Partitioning 

Soil Adsorption/Mobility: The relatively low predicted soil adsorption coefficient (K oc 
= 1) for trichloroacetic acid indicates that adsorption to soil, sediment, and suspended solids is 
not a significant fate process. Several laboratory and field soil studies confirm that 
trichloroacetic acid shows little sorption to soils. As a consequence, trichloroacetic acid has the 
potential for high mobility in soil (HSDB, 1996). 

Volatilization: The very low predicted Henry's Law constant for trichloroacetic acid 
(<10' 7 atm-m 3 /mol) indicates that minimal volatilization is expected from water bodies. Because 
of its relatively low vapor pressure (<1 mm Hg), minimal volatilization from soil surfaces is 
expected (HSDB, 1996). 

Bioconcentration: Bioconcentration factors measured in carp range from 0.4 to 1.7. 
Therefore, bioconcentration in aquatic organisms should not be significant and there is little 
potential for biomagnification in the food chain (HSDB, 1996). 

13.3.3.3.3 Transformation and Degradation Processes 

Biodegradation: Trichloroacetic acid has been demonstrated to be undergo 
biodegradation under aerobic conditions in soil and in laboratory tests with activated sludge 
inocula (half-lives on the order of weeks to months). However, a noticeable lag period was 
observed (i.e., a period in which slow degradation was followed by rapid degradation). 
Degradation appears to be favored by warm moist conditions conducive to high microbiological 
activity (HSDB, 1996). 

Photodegradation: Based on the estimated reaction rate constant of trichloroacetic acid 
with hydroxyl radicals, the estimated half-life of trichloroacetic acid in the atmosphere is about 
31 days. No information is available on the photolysis of trichloroacetic acid. However, 
monochloroacetic acid does not appreciably absorb UV light above 290 nm and thus will not 
directly photolyze; the presence of sensitizers such as p-cresol and tryptophan that generate 
superoxide radicals has been shown to increase the rate of photodechlorination by up to 16-fold 
(HSDB, 1996; Howard et al., 1991). 

Hydrolysis: No information is available on the hydrolytic half-life of trichloroacetic 
acid. However, the hydrolytic half-life of monochloroacetic acid is on the order of years based 
on the results of darkened controls during photolysis experiments (HSDB, 1996; Howard et al., 
1991) 


117 




13.4 


HUMAN EXPOSURE AND POPULATION ESTIMATES 


13.4.1 General U.S. Population 

Based on available data, the general population could be potentially exposed to 
trichloroacetic acid through ingestion of drinking water and foods contaminated with this 
chemical. 

13.4.2 Occupational Exposure 

Estimates from aNIOSH survey conducted between 1981 and 1983 show that 35,124 
employees in the U.S. were potentially exposed occupationally to trichloroacetic acid (IARC, 
1995). This potentially exposed population were employees in seven different industries and 
1,562 plants (IARC, 1995). 

Trichloroacetic acid (3-116 mg/g creatinine) was found in the urine of employees in the 
metal degreasing industry. These employees were exposed to trichloroethylene (HSDB, 1996). 

13.4.3 Consumer Exposure 

Data were not found for consumer exposures. 

13.5 CHAPTER SUMMARY 

Table 13-2 summarizes the findings of trichloroacetic acid. 


Table 13-2. Trichloroacetic Acid Summary 



Estimates 

Support 

Uses 

Chemical intermediate; herbicide 

Well documented data 

Production 

More than 2,270 kg 

1976 data 

Releases 

No available data 


Properties/Fate 

Water soluble; no significant 
bioconcentration is expected 


Media Levels 

Air: no data 

Drinking water: 4.2 to 161 ug/1 
Raw water: 60 to 1,630 ug/1 


General Population 
Exposure 



Special Population 

35,124 employees potentially 

Data from early 1980s 


118 


























14.0 DICHLORO-VINYL CYSTEINE 

No information is readily available for this chemical. 












REFERENCES 


Agency for Toxic Substances and Disease Registry (ATSDR). (1990) Toxicological profile for 
cis-l,2-dichloroethene, trans-l,2-dichloroethene, 1,2-dichloroethene. Update draft. Atlanta, GA. 

ATSDR. (1995) Toxicological profile for 1,1,1-trichloroethane. Update. Atlanta, GA: Agency 
for Toxic Substances and Disease Registry. 

ATSDR. (1996a) Toxicological profile for 1,2-dichloroethene. Update. Atlanta, GA: Agency 
for Toxic Substances and Disease Registry. 

ATSDR. (1996b) Biennial Report to Congress (1991 and 1992) Atlanta, GA: U.S. Department 
of Health and Human Services, Centers for Disease Control and Prevention, ATSDR. Internet 
site: www.dhhs.gov. 

ATSDR. (1997a) Toxicological profile for trichloroethylene. Update. Atlanta, GA: Agency for 
Toxic Substances and Disease Registry. 

ATSDR. (1997b) Toxicological profile for tetrachloroethylene. Update. Atlanta, GA: Agency 
for Toxic Substances and Disease Registry. 

American Conference of Governmental Indusrial Hygienists (ACGIH). (1995) Threshold limit 
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